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Why metrication matters

This is rather a long article so I have broken it into 2 parts.

The first part (5 pages) is a simple summary of why the metric system has been successful, and the second part (31 pages) is where you will find more detailed facts, arguments, and discussion points that you can use in your own metrication campaign. You might like to refer to the second part if you need to argue for the metric system at your home, at your school, at your college, or at your work.


Metrication matters to all of us because:

  • metrication makes our businesses more profitable,
  • metrication makes our calculations simpler,
  • metrication makes our cooking easier and more reliable,
  • metrication makes our costs less,
  • metrication makes our dealings with others more open and honest,
  • metrication makes our export income greater,
  • metrication makes our imported goods cheaper,
  • metrication makes our international dealings friendlier,
  • metrication makes our learning easier,
  • metrication makes our lives safer and more secure,
  • metrication makes our schools and colleges more effective, and
  • metrication makes our work more efficient.

Pat Naughtin, our principal speaker says: 'Whenever I give keynote speeches or run training seminars, I ask people "Why metrication matters to them?".

These comments are from feedback sheets written by people in companies that have had successful metrication upgrades. Participants completed the line:

'After successful metrication there is ... '

  • Better morale
  • Getting it right first time
  • Greater accuracy
  • Greater customer happiness
  • Less customer unhappiness
  • Less cheating
  • Fewer mistakes
  • Less repeating things
  • Less staying back to fix things not done right first time around
  • Management sleeping better at night
  • More happiness
  • More harmony
  • More honesty
  • More pleasant working atmosphere
  • More togetherness because we all feel better valued
  • People feeling valued because of less niggling over errors
  • Shorter meetings

Clearly, metrication matters to many people.

From Pat Naughtin's notes:

While I was thinking about why metrication matters, I jotted down some of the reason why I thought that it did, and why the metric system has been so successful. My writing looked a little like this:

Metrication matters to many people.

Why is it that metrication matters?

Why is the modern metric system so successful?

It is a system.

It is universal.

It is coherent.

It is capable of use in all human activities.

It is fair and equitable to everyone who uses it.

It is simple.

It has support - international and national.

It is fundamental to all measures.

It is unique.

It is legal

I soon realised that I could arrange these words so that the initial letters formed an acronym, a single word that adequately describes the progress of the metric system over the last 200 years.

I then wrote:

The modern metric system, also known the International System of Units (SI) is a:

System that is Universal, Coherent, Capable, Equitable, Simple, Supported, Fundamental, Unique, and Legal.

When I spelled out the initial letters of these words, this became:

The modern metric system, also known the International System of Units (SI) is:


I found this acronym, and the ideas behind it, useful to focus my thoughts when writing this article to help support your decision to upgrade to the metric system and for you to become a metrication leader.

Part 1 - Summary

This article has ten points each of which is based on a word from this acronym.


The modern metric system also known as SI, the International System of Units is a:

System that is Universal, Coherent, Capable, Equitable, Simple, Supported, Fundamental, Unique, and Legal.


The metric system is the only measurement method ever developed as a complete system. All previous attempts used random developments at different places, at different times, and for different purposes.


The metric system has been gradually adopted by all of the world's people. Despite often-vigorous opposition, the metric system has always been successful.


Because the metric system was developed as a complete system, it was possible to design it so that it has an internal consistency. Its internal coherence means that if you learn one part of the metric system you can easily extend your knowledge to all other parts.


All crafts, trades, and professions can successfully use the metric system. Although the structure of the metric system is quite simple, it can be used in every human activity.


The metric system is fair and just to all who use it.


The metric system uses only 7 base units and 22 units with special names - 29 units in all. There are now only 20 old measures left that are non-SI units currently accepted for use with the International System.


International treaties and research keep the metric system modern and forward looking.


The metric system is the only system used internationally. It is now fundamental to all measurements, both old and new.


The metric system is unique because: it was planned; it is decimal; it has prefixes; and it is human in scale. It is unique because there has never been a measuring system like it.


Legislation in every country in the world supports the metric system. It is often the sole method of measurement recognised by governments. International agreements also support the metric system so that contracts written in metric units have validity across international borders.

Part 2 - detailed information

The metric system is a System

The metric system is a system that can eliminate measuring confusion. As a system, it ensures that quantities and units are uniform in concept and style. The metric system is a truly single, standard, system that is able to measure anything in any craft, trade, or profession.

The metric system is a system of measuring units, designed and planned with each unit as part of a whole. This is why its formal name is 'The International System of Units' and its initials are SI from its French name, 'Le Systeme International d'Unites'.

The metric system has many advantages over all of the older pre-metric methods of measurement used in the world before 1790. The advantages of using the metric system include economic, social, educational, and psychological benefits.

In contrast, the old pre-metric measures lacked coordination of any kind. People had to use a great many different, incompatible, and largely incomprehensible, methods to measure. This caused (and continues to cause in many places) a great deal of unnecessary friction and costs.

The metric system is Universal

The metric system is universal because it works anywhere and everywhere in space and time. It works wherever you are right now; it works at the top of Mount Everest; it works at the bottom of the Mariana Trench; it works on the surface of the moon; and in deep space in all the galaxies of the universe. The metric system also works today, tomorrow, next week, and it will continue to work in the next millenium.

Everyone in the world uses the metric system and everyone in the world uses the metric system every day. Yes, that's right, even the people in the USA use the metric system every day:

  • To measure the electricity in lights, heaters, and TVs.
  • To design and make all new cars.
  • To design and build new space vehicles.
  • To analyse breakfast cereals.
  • To measure drinks such as wine, beer, whisky, and most soft drinks.

The metric system is the international standard used by every nation in the world (including the USA) for international dealings such as trade, and for international agreements such as treaties on drugs, climate, and pollution control.

Products designed in non-metric units or using non-metric standards can cause serious maintenance and compatibility problems for customers; this can place the manufacturer at a serious disadvantage. As all nations in the world now use the metric system, it gives predominately metric nations have distinct commercial and trade advantages. If any manufacturer wishes to compete on the world market and deal with the USA, they have to absorb the additional costs of dealing with multiple methods of measurement - the metric system and all the old heritage measures.

People who have never left the USA might not realise that their customary inch-pound measures are practically unknown in other countries. For more than 95 % of the world population, the metric system is the customary system of units, and it has been for more than 100 years.

People in countries other than the USA are familiar with and expect - actually prefer - products made to metric specifications. They are neither familiar with nor comfortable with the inches, ounces, pints, and pounds used in the USA. On the shelves of shops in other nations, inch-pound products from the USA are at a disadvantage.

In today's highly competitive global markets, any disadvantage quickly translates into lost sales and fewer exports. Manufacturers in the USA simply cannot export items, such as appliances and building materials that use non-metric measures. As this inevitably leads to less domestic economic growth in the USA, with fewer new jobs, the most important loss may be to the USA's standard of living.

If the economy of the USA is to grow, exports have to be increased. It has been estimated that each $1 billion in exports from the USA, supports almost 20 000 jobs and that more than seventy million Americans work in export-related jobs with higher than average pay.

For most Americans, most of the names of old measures are essentially meaningless and are useless for practical calculations. In spite of all the extra time spent on science and mathematics education in the USA, and despite all of the training in the use of various conversion factors, very few Americans know how to convert between gallons and cubic feet or between inches and miles.

The metric system is Coherent

Coherence is not an easy concept to understand so here are a few statements about what it means in practical terms.

  • The metric system is coherent in its design, so there are no conversion factors to memorise - there aren't any.
  • The metric system is coherent in that it is consistent with the decimal numbers we all use every day.
  • The metric system is coherent in that it provides a logical system of units where all the symbols are treated mathematically - just like numbers.
  • The metric system is coherent in that it is logically consistent - all parts of the metric system are treated the same way, using the same techniques.
  • The metric system is coherent in that there is only one unit for each quantity. This means that it is never necessary to change from one unit to another within the metric system.

Compare this with the old inch-pound measures that come with a bewildering, random and completely unsystematic set of conversion factors. Most pre-metric measures have multiple origins and complex, often obscure histories.

Consider these everyday questions using old measures.

  • How does the energy of a hamburger (measured in large Calories) compare with the energy of natural gas (measured in therms), the energy in oil (measured in barrels of oil equivalents), or the energy of earthquakes (measured on the Richter scale)?
  • Which is heavier - an ounce of gold or an ounce of lead? (Answer: an ounce of gold.)
  • Which is heavier - a pound of gold or a pound of lead? (Answer: A pound of lead.)
  • How does the price of gold (measured in Troy ounces) compare with the price of lead (measured in avoirdupois pounds)?
  • How does the power of an electric heater (labeled in watts) compare to the power of a gas heater (labeled in Btu/h) or an air conditioner (labeled in horsepower)?
  • How does water flow measured in acre feet per year compare to a million gallons per day?

In 1860, the British Association for the Advancement of Science (BAAS) promoted the idea that the metric system could be a coherent system without any internal conversion factors at all.

In 1885, to achieve this internal coherence the BAAS chose to use some units rather than others. After a false start with the centimetre, gram, and second, which were proved to be too small, the BAAS chose the more practical metre, kilogram, and second as the coherent units.

In 1901, Giovanni Giorgi in Italy, realised that electrical units could also be a part of the metric system's coherence. This coherence idea developed until it became a core part of the International System of Units (SI) in 1960. The International System of Units (SI) is the modern coherent version of the metric system. The SI is the foundation of the metric system we all use today.

Energy and power

This lack of ability of old measures to lead to understanding can lead to very serious problems in the world. Consider the world's pressing need to understand how we use our limited energy supplies and how quickly we use them. These questions directly relate to global warming.

Fundamental concepts such as energy and power are essentially simple in concept but they often confuse politicians because of the numerous ways they are measured with so many unrelated units. This complexity makes it difficult, if not impossible, for politicians to understand even basic quantitative information about the physical world around them. To understand the total world energy issue using old measures is quite difficult (even for scientists and engineers) and almost completely impossible for politicians and the rest of us.

If you want to begin to comprehend global warming, you need to have a working knowledge of most of these 93 old pre-metric energy measures because in the year 2007 they are still in use:

Atomic energy unit, barrel oil equivalent, Billion electron volts, British thermal unit (0 C), British thermal unit (16 C), British thermal unit (20 C), British thermal unit (32 F), British thermal unit (4 C), British thermal unit (60 F), British thermal unit (68 F), British thermal unit (international), British thermal unit (ISO), British thermal unit (IT), British thermal unit (mean), British thermal unit (thermal), British thermal unit (thermochemical), calorie, Calorie, calorie (16 C), Calorie (16 C), calorie (20 C), Calorie (20 C), calorie (4 C), Calorie (4 C), calorie (diet calorie), Calorie (diet kilocalorie), calorie (int.), Calorie (int.), calorie (IT), calorie (International Steam Table), Calorie (it), Calorie (international steam table) , calorie (mean), Calorie (mean), calorie (thermochemical), Calorie (thermochemical), calorie (USA Customary), Calorie (USA Customary), Celsius heat unit (int.), coulomb volt, cubic centimetre atmospheres, cubic foot atmospheres, cubic meter atmospheres, dutys, dyne centimetres, electron volt, erg, foot-grains, foot-pound force, foot-poundal, gigaelectronvolt, gram calorie, gram calories (mean), hartree, horsepower hours, horsepower hours (metric), inch pound force, Kayser, kilo, kilocalorie (16 C), kilocalorie (16 C), kilocalorie (20 C), kilocalorie (4 C), kilocalorie (4 C), kilocalorie (diet kilocalorie), kilocalorie (int.), kilocalorie (int.), kilocalorie (IT) (International Steam Table) , kilocalorie (mean), kilocalorie (thermochemical), kiloelectronvolt, kilogram calories (int.), kilogram force meter, kiloton TNT equivalent, kilowatt hour, kilowatt minute, kilowatt second, megaelectronvolt, megaton TNT equivalent, megawatt hours, newton meter, newton meters, Q unit, quadrillion, quad, Rydberg, therm (EC), therm (US), thermie (16 C), ton TNT equivalent, tonne coal equivalent, tonne oil equivalent, watt hour.

What is even more concerning is that when converting from one to another, all these 93 different energy words also require 8556 conversion factors to convert from any one measure to any other if energy issues - such as global warming - are to be understood at even a basic level.

Remember, in the International System of Units (SI) there is only one unit for energy:


Therefore conversion factors are not necessary - there aren't any.

Using the metric system to consider energy is comparitively easy. We know that energy is measured in joules and that we will probably need to use some large prefixes to understand our energy use on a global scale. Here are some figures to consider.

  • If you are an average teenager you will need 11 000 kilojoules or 11 megajoules of food energy each day. This is 77 megajoules each week - 330 MJ each month - and about 4000 MJ of energy for a whole year. You might even like to think of this as four gigajoules per annum (4 GJ/a) as there are 1000 megajoules in a gigajoule. Even a hardworking construction worker only needs about 5 gigajoules per annum (5 GJ/a).
  • In a temperate climate, an average family household uses a bit over 100 gigajoules of energy in a year. This might go up to 150 GJ in a cold climate.
  • In 2003, the USA used 112 exajoules of energy that was made up from: 42 exajoules from petroleum, 26 exajoules from natural gas, 26 exajoules from coal, 11 exajoules from nuclear energy, and 7 exajoules from renewable energy.

Similarly, when considering power, quantities are also much easier to express in the metric system. For example, 500 watts is much simpler to say and to write than any of these equivalent amounts:

500 watts = 0.05098 horsepower (boiler), 0.1194 kilocalories per second, 0.142 commercial refrigeration tons, 0.4739 British thermal unit per second, 0.6702 horsepower (electric), 120 thermochemical calories per second, 1700 British thermal units per hour, 10 300 large Calories per day, 22 000 feet pound-force per minute, 28.43 British thermal unit per minute, 1706 British thermal unit per hour, or 368.8 foot pound-force per second.

The metric system is Capable

From its beginning, the metric system had the motto:

'For all people; for all time'.

Marie Jean Antoine Nicolas de Caritat Condorcet

All of the world's people, in all of the world's crafts, trades, professions, and in all other occupations can capably use the metric system for all of their activities every day.

The seven base units, the derived units, and the prefixes of the metric system provide suitable units for everyone to use in all of their activities.

The metric system is capable of measuring things that are very small and things that are very big. For example:

The diameter of an electron is about 6 femtometres and the diameter of the whole Universe is about 200 yottametres.

The mass of a bacteria is about 1 microgram and the mass of the whole Earth is about 6 000 yottagrams.

The metric system favors the easier-to-use decimal fractions rather than vulgar (or common) fractions, which means that you can use your calculator to check your metric system calculations.

You can significantly reduce costs when you reduce or eliminate calculation and conversion errors. The metric system costs less to use than any of the old pre-metric methods and much, much, less than any attempt to use mixed methods of measuring that muddle old measures with metric units.

Costs vary in different industries but experience has shown substantial long cost savings soon overcome any initial set-up costs. Most industries keep conversion costs to a minimum by simply planning to replace old equipment as it wears out, with new metric equipment or by upgrading to metric units when new products are developed.

It is obviously much less efficient for a business enterprise - or an industry - or a whole nation - to use two (or more) measurement methods instead of one. For a company, two measurement systems usually means two sets of tools, parts, two sets of product specifications, and two sets of marketing literature, as well as repeated conversions among units. By adding uncertainty and potential confusion to industry standards, using two measurement systems industry-wide multiplies the inefficiencies suffered by individual companies.

Surprisingly, some argue that a transition to metric units would be too expensive. This arises from the false conjecture that initially it costs effort, money, and time to make the change to the metric system. However, experience in thousands of companies all around the world has shown that:

  • This initial expense can be reduced to very small amounts by careful goal setting and planning, and
  • This problem completely disappears once the changeover is underway and the positive benefits, such as increased profits, are rolling in.
  • There are even advantages to be gained by industry during a metrication upgrade.

During an upgrade to the metric system, many companies have been able, simultaneously, to streamline their operations, eliminate inefficiencies, and reduce their inventories. The standardization of fasteners, components, and sub-assemblies increases the efficiency and productivity of all manufacturing processes.

When companies upgrade fully to the metric system, they are often surprised to discover how little it cost and how much the metric transition has increased their profits. Upgraded metric companies frequently report positive benefits for their new metric products and services.

When products destined for both foreign and domestic markets are designed and manufactured to the same, metric, specifications, companies are able simultaneously to:

  • streamline all operations (from purchasing, through manufacturing, to sales and marketing),
  • eliminate inefficiencies,
  • reduce inventories,
  • eliminate overlapping product lines,
  • standardise fasteners, components, and sub-assemblies,
  • increase the efficiency and productivity of all manufacturing processes,
  • increase profits, and
  • find new customers both domestically and internationally.

Many companies are now seeing that temporary metric conversion costs are an investment that can reduce current costs and in a surprisingly short time provide a large return.

The metric system is Equitable

One of the key arguments for using the metric system is that it is fair to everyone who uses it. If you buy a litre of milk, then everyone in the milk production, processing, marketing, and retailing chain is using the same definition of a litre. This is because they are all using the same international standard litre for their measuring. The metric system is the same in all trades and in all professions, so it is the same for all nations, for all companies, and in all workplaces.

The metric system is equitable and fair to all the people of the world because it is based on established international standards and treaties and because its international foundation is not based on politics that are peculiar to a particular nation or to a particular time; the metric system is not altered by political whimsy or corruption.

We can compare this with some of the old ways when powerful groups deliberately corrupted measuring methods to serve their own ends. Customer confusion was the goal of many old measures.

Consider the case of the 'intra muros' and 'extra muros' bushels that traders used in 18th century France. These terms, 'intra muros' and 'extra muros', mean inside the walls and outside the walls. Traders bought grain from farmers using 'extra muros' bushels that were as large as they could get away with; they then sold grain in the city using 'intra muros' bushels that were quite small.

This process of having different sets of measures for buying and selling goes back a long way in history.

Deuteronomy in the King James Bible (Scholars say that this was written before the latter part of the 7th century BCE) says:

Thou shalt not have in thine house divers measures, a great and a small. But thou shalt have a perfect and just weight, a perfect and just measure shalt thou have. (Deuteronomy 25:14/15)

The Koran (written between the years 610 and 632) says:

Woe to those who give short weight! Who when they measure against others take full measure; but when they measure to them or weigh to them, diminish! (Koran Sura 83).

There have also been measures created that make calculations very difficult or near impossible. Consider the case of the oil barrel.

The first thing to know about the oil barrel is that it never existed. Oil is not put into standard barrels when it is pumped out of the ground - and it never was! An oil barrel is a simply made up container that, in theory, holds 42 American (USA) gallons and this rounded whole number translates to 34.9726 Imperial gallons, 5.6146 cubic feet, 158.984 litres or 0.136 tonne (approx). When you notice that the West Texas crude oil price is (say) $63.60, how can you relate this to the $1.30 per litre that you are paying when you fill up your car? (By the way, $63.60 is equivalent to 40 cents per litre and $1.30 is equivalent to about $4.10 per gallon in the USA.)

Compare this transaction to buying a kilogram of sugar. When you order a kilogram of sugar, you can be reasonably sure that you will be supplied with a kilogram of sugar or even a little bit more. When you use the metric system, costs can be easily observed; everything can be discussed out in the open. Unlike the oil industry, there is none of the inbuilt deliberate confusion, using non-existent containers such as the barrel, that linguists refer to as obfuscation.

The demand for an equitable system of measures has been a demand placed on all measuring methods from the beginning of recorded history.

For example, in the King James version of the Bible there is the instruction:

'Just balances, just weights, a just ephah, and a just hin, shall ye have ... ' (Leviticus 19:36).

As the book of Leviticus is one of the earlier books of the Bible, Bible scholars tell us that these demands for honest weights and measures have been around for about 10 000 years.

The metric system is Simple

On a practical level, when you use the metric system, you immediately know which unit to use. If you are measuring a length or a distance, you know that you will use some form of the metric unit: metre.

If you are measuring inside one of your skin cells, you might use nanometres. If you are measuring the diameter of a hair on your head, you might use micrometres. If it's the width of your little fingernail, you might use millimetres. If you are measuring from here to the door, you might use metres. If you are measuring from here to your capital city, you will probably use kilometres, and if it's the width of a whole continent, you might use megametres. As you can see, all of these use some form of the same unit: metre.

You might like to compare this simplicity of the metric system with the many hundreds or thousands of old unit names that you know.

Here is a complete list of metric units for length:

yoctometre, zeptometre, attometre, femtometre, picometre, nanometre, micrometre, millimetre, metre, kilometre, megametre, gigametre, terametre, petametre, exametre, zettametre, yottametre

And here are some examples of non-metric length measures currently in use - this is not a complete list - there are many others.

agate (printers), air miles, angstrom unit, astronomical unit, cable, calibre, chain (international), chain (USA survey), drill number, European shoe size children's, European shoe size men's, European shoe size women's, fathom, feet survey USA, fermi, foot (imperial), foot (USA survey), furlong, gauge (plate), gauge (Washburn & Moen), gauge (wire), gauge USS standard plate, hand (international), hand (metric), hand (USA), inch (Canadian), inch (Cape), inch (Enfield), inch (imperial), inch (USA survey), Japanese shoe size children's, Japanese shoe size men's, Japanese shoe size women's, light minute, light second, light year, link (international), link (USA survey), microinch, mil, mile (Imperial), mile (nautical), mile (USA survey), military pace, milli-inch, nail penny, pace (geometrical), pace (military), parsec, perch, pica (computer), pica (printer), point (USA computer), point (USA printer), point computer , pole, PowerPoint centimetre, range, rod (imperial), rod (USA survey), screw number, shoe size children's (UK), shoe size children's (USA), shoe size men's (UK), shoe size men's (US), shoe size women's (UK), shoe size women's (US), shotgun gauge, township, vinyl gauge, wire gauge, wire gauge (Birmingham), wire gauge (American), yard, and many, many more.

And these are only for length - there are much longer lists for old pre-metric measures for such things as capacity and energy.

Base units and derived units

The metric system is simple as there are only seven base units. All other units that people need are derived units based on these seven. This gives the metric system an enormous range and great flexibility. For everything that you need to measure, the metric system has a single unit.

These single units all have simple names. In the whole of the metric system, there are only 7 base units and 22 units with special names - 29 units in all. Almost all of the 29 individually named units are limited to highly specialised activities. Most of us need only learn a few of these, and we usually learn these quickly and easily.

Here are the 7 base units:

metre, kilogram, second, ampere, kelvin, mole, and candela,

and 22 derived units with special names and symbols:

becquerel, coulomb, degree Celsius, farad, gray, henry, hertz, joule, katal, lumen, lux, newton, ohm, pascal, radian, siemens, sievert, steradian, tesla, volt, watt, and weber.

That gives you fewer units to memorise and almost no conversion factors. As there is only one unit for each physical quantity in the metric system, conversions are rarely necessary.

  • In the metric system, there is only one unit for measuring length - the metre.
  • In the metric system, there is only one unit for measuring area - the square metre.
  • In the metric system, there is only one unit for measuring volume - the cubic metre.
  • In the metric system, there is only one unit for measuring mass - the kilogram.
  • In the metric system, there is only one unit for measuring power - the watt.
  • In the metric system, there is only one unit for measuring energy - the joule.
  • In the metric system, there is only one unit for measuring time - the second.
  • In the metric system, there is only one unit for measuring force - the newton.

Astute readers will notice that areas might be in hectares, volume might be in litres, and time might be in minutes, hours, and days. This is true, and it is because we have inherited some older pre-metric units that are 'Non-SI units accepted for use with the International System', 'Non-SI units accepted for use with the International System whose values are obtained experimentally', or 'Other non-SI units currently accepted for use with the International System'. Altogether, there are only twenty of these left, as all of the many hundreds and thousands of others have gradually disappeared from official lists. The twenty that are left are:

Angstrom, are, astronomical unit, bar, barn, bel, day, degree, electronvolt, hectare, hour, knot, litre, minute, minute, nautical mile, neper, second, tonne, and unified atomic mass unit.

Yes, that's right minute occurs twice. The second 'minute' and the second 'second' listed here are measures of plane angle not as measures of time. (It's even difficult to write about old measures.)

The metric system is easy to learn

Students in the USA waste at least half a year of mathematics education trying to develop skills in converting between different measurements. Currently in the USA, huge blocks of time are spent learning about the cumbersome old inch-pound measurements, including learning how to do tedious conversions between metric and old inch-pound units. They ask questions like:

How high is Mount Everest in metres, if it is 29012 feet high.?

How many centimetres are there in 8 inches?

How many millimetres are there in 5 yard 2 feet and 11 inches?

How many miles are there in 200 kilometres?

How many kilograms are there in 3 tons 5 hundredweight 3 quarters and 26 pounds?

How many statute miles are there in 17 nautical miles?

How much does a trader make if he buys 25 pounds of tea for $18.00 and sells it for $43.00 per kilogram?

In a study of these issues, 'Education System Benefits of U.S. Metric Conversion' (published in Evaluation Review, February 1996), Richard P. Phelps, reckoned that teaching solely metric measurements could save an estimated 82 days of mathematics instruction time annually, and that this wasted time was costing taxpayers in the USA over 17 billion dollars per year.

Educational practices that are more worthwhile could readily replace much of this time and economic loss. This applies at all levels from elementary grade schools to post-graduate engineering courses.

Compare this with the ease that building workers in Australia learn all - repeat all - the metric units needed to build a house in Australia. This complete set takes only a few minutes to learn.

1000 millimetres = 1 metre1000 metres = 1 kilometre
1000 millilitres = 1 litre1000 litres = 1 cubic metre
1000 grams = 1 kilogram1000 kilograms = 1 tonne
1 metre x 1 metre = 1 square metre

Because the metric system is easier to learn than any old pre-metric methods, many educational improvements are possible with revised metric school and college curricula.

On a broader scale, any workforce that is able to routinely use the metric system is better able to compete in the global marketplace, and any national population that is highly skilled in counting, measuring, and calculation is an asset for that nation's economic, cultural, and social progress. These benefits occur because following a transition to the metric system, education and training in all key subjects becomes much more efficient.

The metric system is Supported

The metric system is the only properly maintained system of measuring units available in the world today because it is supported by international treaties and by national legislation. The most important of these international treaties is the 'TREATY OF THE METRE'. Under this international treaty, the modern metric system is constantly monitored and updated whenever new knowledge of measurement becomes available. This makes sure that the metric system remains the world measurement leader. In contrast, the old pre-metric measures essentially stopped evolving more than 200 years ago.

Because the metric system is supported internationally, there is a uniform metric system style for expressing all measured quantities internationally. The metric system is also supported by various internationally approved conventions, such as standards organisations, that govern the use of terms and symbols. This keeps the metric system the same all around the world.

The metric system is Fundamental

Did you know,

that there have never been any old pre-metric measures for electricity? The USA has had to copy all its electrical units (volt, ampere, watt, ohm) from the metric system.

Did you know,

that computers are designed from their smallest parts using nanometres and micrometres? Their circuit boards and cases are then designed and built using millimetres. Finally, the size of the screen and the size of the disks are dumbed down from millimetres to inches to avoid your anger at having to use a fully metric computer.

Did you know,

that all cars in the world - including all the cars in the USA - have been designed and built in metric units only since the mid 1970s?

Did you know,

that the metric system is now the fundamental basis for all of the world's old pre-metric measures? For example, that the USA has based the length of a foot, a yard, a chain, and a mile on metric standards since 1893?

T. C. Mendenhall, then Superintendent of Weights and Measures, with the approval of the Secretary of the Treasury, decided that the international metre and kilogram would in the future be regarded as the fundamental standards of length and mass in the United States, both for metric and customary weights and measures. This decision, which has come to be known as the "Mendenhall Order", was first published as Bulletin No. 26 of the Coast and Geodetic Survey, approved for publication April 5, 1893, under the title, "Fundamental Standards of Length and Mass";

Did you know,

that a nautical mile, and therefore an air mile, is exactly 1852 metres long?

Did you know,

that in 1959, by agreement between the English speaking nations, the inch was re-defined as exactly 25.4 millimetres? This was done because during World War II there was considerable difficulty in exchanging precision equipment because different countries were using different inches - inches that had slightly different lengths. Now, whenever you refer to an inch (and by extension) also a foot, a yard, and a mile, you are really referring to a metric inch, a metric foot, a metric yard, and a metric mile. After the redefinition of the inch, to the metric inch, industries in English-speaking countries - apart from the USA - have decided to abandon the inch entirely for precision work.

Did you know,

that the world standard railway gauge is now 1432 millimetres?

Did you know,

that the, so called, 12 inch and 10 inch vinyl records were designed to be 300 millimetres and 250 millimetres respectively?

Did you know,

that because the metric system is now so fundamental to all of the old pre-metric measures, the USA now finds itself in a position where economic realities, international standards, and the shortcomings of the old pre-metric methods force it to use the metric system daily for all of its activities? To say that you are using 'good old' feet and inches when you describe your height is simply a delusion - you are probably using the almost brand new, post 1959, metric feet, and metric inches.

The metric system is Unique

The metric system is unique - there has never been a measuring system like the metric system before - never in the history of the world. The metric system is unique because it:

  • is human in scale.
  • is decimal,
  • has prefixes, and
  • was planned,

The metric system is human in scale

As the metric system developed, the measurements selected were on a convenient scale for measuring humans. For example:

  • Your hand is about 100 mm across if you include your thumb.
  • For most men the width of their little fingernail is close to 10 mm.
  • For most women the width of their fingernail on their long finger is close to 10 mm.
  • Your hand span is between 200 mm and 250 mm.
  • Women's walking pace is about 500 mm.
  • Men's stretched walking pace is about 1000 mm or 1 metre.
  • A marching pace for both men and women is 750 mm.
  • Most people walk at about 100 metres per minute.
  • If you walk briskly for an hour your will walk 6 kilometres (6 km/h).
  • The body mass of most women is between 50 kg and 80 kg.
  • The body mass of most men is between 60 kg and 90 kg.
  • The average height of men is 1.75 metres.
  • The average height of women is 1.65 metres.
  • Most newborn babies are close to 500 mm long.
  • The lengths of most people's feet are close to 250 mm.

From the day we are born, we confront the metric system. Newborn babies have their mass determined on a set of scales almost immediately after their birth. Most babies are about 3.5 kilograms (small babies are nearer to 2.5 kg and big babies are closer to 4.5 kg). The reason that babies have their mass determined so quickly is so that medical staff can treat the baby with medicines if it becomes ill, and these medicines are dosed in milligrams per kilogram, or in micrograms per kilogram. (Sadly, however, there are mothers, grandmothers, sisters, cousins, and aunts who dumb down the baby's mass to pounds and ounces, possibly putting the health of their babies at risk).

The metric system is decimal

The metric system uses the same decimal numbers that we use for counting and calculating. This means that you can do any metric system calculations on an ordinary calculator.

Suppose you want some vinyl tiles for a bathroom floor that is 3.450 metres by 2.535 metres, your metric calculation of the floor area - done on your calculator - would be:

Floor area = 3.450 x 2.535 = 8.74575 square metres

You would probably round this up to 9 square metres to allow a little for cutting.

To do this in old pre-metric measures you would need to work out:

12 feet 11 and 7/8 x 8 feet 3 and 5/8 = _______ square yards

I will leave this calculation to you. Note that your calculator is of little use here.

Because the metric system is a decimal system, it has a simple set of conversion factors (tens, hundreds and thousands) that are consistent across all measurements. These are known as 'multiples of ten' or sometimes 'powers of ten'.

As you use the metric system, you will never have to deal with 2s, 3s, 4s, 12s, or 16s (as you do with 2 pints in a quart; 3 feet in a yard; 4 quarters in a hundredweight; 12 inches in a foot; or 16 ounces in a pound). You don't have to remember any other strange numbers like 231 (cubic inches in a gallon (USA)), 2240 (pounds in a long ton), 5280 (feet in a mile) or hundreds of other similar diversities.

Even with 'difficult' numbers such as thirds, the metric system allows you to treat them with ease. Suppose you want to divide a kilometre of wire into 3 equal parts. Obviously, each part will be 1/3 of a kilometre long but this doesn't help you decide exactly where to cut. So, think of the kilometre as 1000 metres - this time you can divide to get 333 metres with a metre left over. You now need to decide how accurate you want the three pieces to be. If you decide on a precision of 1 millimetre, you could divide the original kilometre into 3 parts of 333.333 metres. If you require more precision, you could even choose micrometres. Clearly, the metric system allows you to decide on your exact levels of accuracy and precision.

By the way, if someone suggests to you that the metric system is not good at vulgar fractions such as thirds, simply ask them to calculate (in their heads) a third of a mile in yards, feet, and inches to the nearest sixteenth of an inch or a third of a pound in ounces to the nearest pennyweight.

In practice, people find that metric dimensions are quite easy to subdivide using a range of factors, as it is easy to move to smaller sub-multiples of metric units. It is also more common in the metric world to use standardised preferred number sequences. For example, in the Australian and British building industries, design dimensions are usually multiples of 600 millimetres. As a result, 2, 3, 4, 5, 6, 8, 10, 12, 15, 20, 24, 25, 30, 40, 50, 60, 75, 100, 120, 150, 200, or 300, can divide common building dimensions without any fractions of millimetres.

The metric system has prefixes

Prefixes are short, convenient, unambiguous, easy-to-pronounce names and letter symbols for powers of ten. In the metric system, there are 20 of them. You can easily choose a unit of the right size for the jobs you do.

Once you know the basic unit of a quantity that you want to measure, then it is easy for you to generate all the other names. Suppose you want to measure a length and you know that in the metric system length uses the unit: metre. Then you would probably choose from this list of possibilities.

1 metre = 1 000 millimetres1 000 metres = 1 kilometre
1 metre = 1 000 000 micrometres1 000 000 metres = 1 megametre
1 metre = 1 000 000 000 nanometres1 000 000 000 metres = 1 gigametre
1 metre = 1 000 000 000 000 picometres1 000 000 000 000 metres = 1 terametre
1 metre = 1 000 000 000 000 000 femtometres1 000 000 000 000 000 metres = 1 petametre
1 metre = 1 000 000 000 000 000 000 attometres1 000 000 000 000 000 000 metres = 1 exametre
1 metre = 1 000 000 000 000 000 000 000 zeptometres1 000 000 000 000 000 000 000 metres = 1 zettametre
1 metre = 1 000 000 000 000 000 000 000 000 yoctometres1 000 000 000 000 000 000 000 000 metres = 1 yottametre

Of course, you could choose from one of these too:

1 metre = 10 decimetres10 metres = 1 decametre
1 metre = 100 centimetres100 metres = 1 hectometre

However, these are chosen much less often because experience in many crafts, trades, and professions have shown distinct advantages in choosing from prefixes that are multiples of 1000 rather than multiples of 10 or 100.

Careful observers have noticed that metrication using millimetres is dramatically faster, cheaper, and smoother than metric conversion using centimetres. The use of centimetres, decimetres, centilitres, and decilitres has proved to be a major disadvantage to direct metrication. This has been a particular problem in traditional women's activities such as cooking, nursing, primary school teaching, and sewing where the use of the centimetre is common.

If you are planning on a successful – and relatively rapid – metrication program it is best to choose prefixes that are multiples of 1000 and to choose them so that the use of fractions, both common fractions and decimal fractions, are eliminated. This means that you should avoid the prefixes, centi, deci, deca, and hecto.

Once you have grasped this idea of changing from one prefix to another, you can readily extend it to the other 29 units of the metric system, as in:

1000 millilitres = 1 litre

1000 grams = 1 kilogram

1000 kilowatts = 1 megawatt

The metric system is logical, easy to understand, easy to learn and it is easy to change between measurements of different sizes. A unit with a prefix attached is a multiple or a sub-multiple of the unit - it is not a separate unit. The prefixes of the metric system allow you to, quickly and easily, change from smaller to larger unit multiples.

Changing between different multiples and sub-multiples of metric units is as easy as shifting a decimal point and changing the name of the prefix. For example, the one and only unit of length in the metric system is the metre - you do not form a separate unit when you attach a prefix. As an example, when you rewrite 2340 metres as 2.340 kilometres you are simple moving the decimal marker three places to the left and adding the prefix 'kilo' before the unit name, 'metre'. No arithmetic was necessary; it's a bit like rewriting 2340 metres as 2 thousand, three hundred, and forty metres.

As another example, to change from 2 metres to millimetres you move the decimal point 3 places to the right - by adding 3 zeroes - and changing the unit name to millimetres.

2 metres = 2000 millimetres

Similarly to change from 5000 grams to kilograms you move the decimal marker 3 places left.

5000 grams = 5.000 or 5 kilograms.

This second example also shows you how to get rid of long rows of excessive zeroes, either before or after the decimal marker; the metric system prefixes can simply eliminate most of these unnecessary zeroes as in:

  • 000 234 metres = 0.000 234 millimetres = 0.234 micrometres = 234 nanometres, or

  • 123 000 000 000 micrograms = 123 000 000 milligrams = 123 000 grams = 123 kilograms.

The metric system prefixes remarkably simplify calculations and reduce the time needed to perform them. The most commonly used prefixes are:

  • milli, used in millilitres, milligrams, and millimetres, and
  • kilo, used in kilolitres, kilograms, and kilometres.

Notice how the preferred prefixes that are multiples of 1000 ensure that moving the decimal marker is made as easy as possible - moving the decimal marker is always 3 places - you only have to decide between going to the left or to the right. This means that in the whole metric system, there are only 16 prefix names to learn (there are still only 20 prefix names if you include those used less often: centi, deci, deca, and hecto).

Generally, the metric system tends not to need fractions. You might choose to use decimals exclusively, thus eliminating the clumsy vulgar (or common) fractions and the even clumsier mixed numbers. Most people who use the metric system regularly tend to prefer to use decimal fractions, that is, if they use fractions at all. They do not use 1/2 a metre when they can easily measure 500 millimetres; they do not use 2/3 of a kilogram when they can easily measure 667 grams.

You can go beyond this. Because the metric system has a standard set of prefixes, you can usually arrange your work without any fractions at all - no vulgar fractions, no mixed numbers, and not even any decimal fractions. The Australian building industry chose not to use fractions with their metric length policy, which read:

So we (the Australian building industry) will use three units of linear measure - metre, millimetre, and kilometre. They are distinct and cannot be confused. In building and construction the centimetre will not be used.

Since the mid 1970s, builders in Australia have not needed to ever think about fractions, whether vulgar (or common), mixed numbers, or even decimal fractions.

The metric system was planned

When you use the metric system, you are only using one single system of units. Other measuring methods arose more or less at random from a multitude of historical sources. The metric system is simple and more logical than any previous methods of measurement ever known because it was logically planned from its beginning.

The metric system developed for about 200 years before its adoption in France. In this chronology, you will see that the metric system developed internationally; no one nation was responsible for its complete development. The metric system was always an international system. Historically, the metric system developed from these ideas:

1585: The initial idea for a decimal measuring system of units came from Simon Stevin (1548/1620) who started life as a bookkeeper in Flanders and who later became a clerk in the Flemish tax office. (The modern name for Flanders is Belgium.)

1668: The English academic, John Wilkins devised a universal system of measurement that had almost all of the properties of the modern International System of Units (SI). It had a 'universal measure of very close to our modern metre that was used to measure length, area, and volume. Wilkins also proposed that his 'universal measure' could be used to determine mass by filling a cube made with a 'universal measure' on each side and filling it with distilled rainwater. Wilkins system was published by the Royal Society in London about 120 years before the French 'philosophes' developed it further into the metric system that they devised in the 1790s.

1670: A French country vicar, Gabriel Mouton (1618/94), from Lyons in France, suggested that a new measurement system could be based on a natural phenomena such as the size of the Earth. In this he repeated many of Wilkins ideas published two years previously.

1740: Cassini de Thury carried out a survey to accurately determine the size of the Earth.

1780 approx: James Watt (1736-1819), a Scottish engineer, promoted the idea that the decimal system should be the basis for any new measuring methods.

1784-89: Thomas Jefferson was ambassador to France where he had a marked influence on promoting the concept of decimal numbers as he had had previously when he, with George Washington, promoted the idea for a decimal currency for the USA.

1787: Arthur Young, a gentleman farmer from England, reported:

In France the infinite perplexity of the measures exceeds all comprehension. They differ not only in every province, but in every district and almost every town.

At that time, France had about 800 names for different measures, and taking into account the different sizes of all these measures in different towns, they had about around 250 000 different measures altogether. All other nations had similar problems but these were not so well documented as they were in France.

1790: The Inspector General of the French Mint, Marie Jean Antoine Nicolas de Caritat Condorcet (1743/1794), asked a friend, Charles Maurice de Talleyrand-Perigord (1754/1838), to put a proposal for a new measurement system to the French National Assembly. Condorcet's system was to be based on a length from nature; it was to have decimal sub-divisions; all measures of area, volume, weight etc were to be linked to the fundamental unit of length; and the basic length should be that of a pendulum which beat at the rate of one second.

The French National Assembly adopted the proposal but, assuming that the new metric system would be fully international, agreement was sought from many other countries. The length of the pendulum soon proved to be a problem; the French proposed a latitude of 45 degrees that was not too far from Paris, the English proposed London, and the USA proposed the 38th parallel that passed quite conveniently near Thomas Jefferson's estate.

1791: Jean Charles de Borda, Chairman of the French Commission of Weights and Measures, resolved the pendulum problem by proposing that the new standard length be 1/10 000 000 of the distance from the pole to the equator of the Earth. This, despite some resistance, became the first standard for the metre.

1792/1798: Delambre and Mechain measured the length of the meridian between Dunquerque in France and Barcelona in Spain so that they could accurately estimate the distance from the equator to the North Pole.

1793: Borda, Lagrange, and Laplace computed a provisional value for the metre based on the survey carried out by Cassini de Thury in 1740. The metric system was passed into law by the French National Assembly and a metre bar together with a kilogram mass were dispatched to the USA expecting that the USA would adopt the new measures. Congress hesitated because the standards were provisional, and Britain and Germany became hostile to the metric system because of the changed definition of the metre.

1798: An International Commission began work with the goal of replacing the provisional values with more precise standards.

1799: Based on the data collected by Delambre and Mechain, an International Commission produced a platinum bar that became the official definition of the metre. After more than 200 years of development (from 1585 to 1799), 1979 June 22 became the legal beginning of the decimal metric system.

The metric system is Legal

The metric system has been adopted as a legal basis for trade in all nations in the world. Anyone who is thinking about doing business internationally knows that all contracts will be written with all physical, chemical, electrical, and electronic measures specified in metric units.

In many nations, contracts written in old pre-metric measures are simply not legal. For example, the Australian Weights and Measures (National Standards) Act stipulates that if units other than the prescribed legal units are used in a transaction, that transaction is void under Australian law. The units that are part of the 'prescribed legal units' mentioned here are, with very few exceptions, those of the metric system as specified by the International System of Units. Legislation like this is common in every country in the world. This means that you need to take special care with your choice of units in the formulation of your contractual arrangements.

Take particular care if you are writing contracts using computer software from the USA as some leading software companies seem to specifically discourage the correct use of the metric system. As you consider what measuring units to use in your next contract, keep in mind that you don't want to end up with a contract that is null and void.


To summarise, the modern metric system also known as SI, the International System of Units is a:

System that is Universal, Coherent, Capable, Equitable, Simple, Supported, Fundamental, Unique, and Legal.

And if you spell out the initial letters of these words, you find what the metric system has been all around the world:

S - U - C - C - E - S - S - F - U - L

Congratulations, and can you help?

Congratulations on taking a major step towards metrication by visiting /Why_metrication.html and for reading to this point on the page.

By reading the information on this web page, and the associated support pages at you'll soon be in an excellent position to advance the goals of your organisation, improve your own career, or to choose business opportunities wisely.

If you enjoyed reading the free metrication information on this web page, please pass it on to your friends, family members, work associates and anyone else who you feel would benefit from knowing more about metrication.

Your action could prevent your family and friends from falling victim to many metrication errors that might cost them years of measurement frustration. Our goal is to educate everyone we can about the simplicity and ease of use of the metric system. In this way your family and friends will gain the positive benefits of using the metric system earlier than others.

By passing this newsletter on to your friends you'll help to prevent them being cheated by measurement fraud, drive measurement fraudsters out of business and make the world a safer place for everyone! Not bad for sending a few emails, or putting a link on your website! On the other hand, if you decide not to pass a reference to this web page along, and your best friend gets cheated because of a measurement misunderstanding, how hard will you kick yourself?

The internet is a fantastic distribution medium. If you pass a reference to the 'Metrication matters' web page (at /why_metrication ) to just ten people, and they do the same, very soon everyone will be better educated (and that's hundreds of millions of people). In fact, you are just six people away from distributing one million copies, so your friends are just five people away! There's no way that I could reach millions of people on my own, so please help! Here are a few distribution ideas:

1 Forward something like this in an email to your friends, associates and relatives. The email can't do any harm, as it cannot contain viruses, plus it's a very short email, so your friends won't mind. Please, do not send the file to anyone you don't know. Spam is one of the worst aspects of the internet, and I don't want to play any part in it.

Dear Friend,

I have been reading and enjoying reading a web page that positively promotes the use of the metric system. It is very easy to read and it is packed with ideas that you can use. The web page is at: /why_metrication.html

Best regards,
Your name

2 Put a reference to /why_metrication.html on your website in a prominent position. You'll add great free content and be doing a good thing for your visitors.

3 If you have read the 'Metrication matters' newsletters, or you are a subscriber, you might like to send an email like this to your family and friends.

Dear Friend,

I have been enjoying reading a free monthly newsletter called 'Metrication matters', and I thought that you might enjoy it too. Just log in at: /newsletter.html

There are links on the sign-up page to the back issues of 'Metrication matters' so you can check if they are right for you before you sign up.

Best regards,
Your name

Many thanks for participating in the distribution the Metrication matters web page.

Cheers and best wishes for your metric future,

Pat Naughtin

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