The metric system, also known as the International System of Units (SI), is the primary system of measurement used throughout the world.

SI was invented to make measurements and calculations easy for everyone to do and understand, regardless of where they were from. It’s why the measurement system is widely used in science and engineering and even has its own international bureau – the International Bureau of Weights and Measures.

It was created over 200 years ago and was designed to be a universal measurement system. The fact that it still stands to this day and is the most used system in the world is a testament to its success.

But when was it invented, and how? That’s what we’ll explore in this article.

The metric system was invented in 1790 by French scientists and was called the decimal metric system. After the French Revolution began in 1789, French scientists looked to create a new system of standard units of measurement to be used in scientific and engineering work.

Prior, there were almost 400 different ways to measure land in the country. This was due to local and regional areas having their own traditional units, which were proving to be inefficient. Therefore, French scientists created a rational system of units that the entire country and world could use. This included units to measure weight, volume, distance, and even time and how they could be interrelated.

But, there were three previous stages of development that eventually culminated in the creation of the modern metric system.

What are the three stages of development for the metric system?

There were three separate stages that were developed at three separate times and in three separate places. It was then put together a fourth time, in 1790, to create the metric system as we know it. However, at the time, it was called the ‘decimal metric system’. Let’s break this down.

Decimal

The decimal part is the oldest of the three as it has been used in many parts of the world throughout human history, such as ancient China, ancient Egypt, and medieval Arabia. However, it wasn’t until 1585 that we began to see its widespread use.

Simon Stevin, a Flemish engineer and accountant, encountered long-winded calculations when working out the amount of interest that banks should charge when lending money. He realized that using decimals would make these calculations much easier and faster. He also realized that decimal numbers could be used when calculating lengths and angles for his engineering work without using fractions, showing that it had broad applications.

His ideas for implementing decimals were published in a book called Disme: the art of tenths in 1585, and it is this book that promoted the use of decimals in calculations. The book was a key piece of literature that influenced British clergyman and philosopher John Wilkins.

System

The second stage of development was the ‘system’. An English clergyman, by the name of John Wilkins, created the plan for a universal system. He released an essay in 1668 outlining the proposal for a ‘universal measure’, and it detailed almost all the elements of the International System of Units as we know it today.

John Wilkins built on Simon Stevin’s idea of decimals and proposed a decimal system with a universal standard of length which could then be used to determine area, volume, and weight. However, he did not invent the word meter and did not use the metric prefixes. Those were developed at a later date.

Metric

The next stage was the development of the word meter. It is widely accepted that the term was first derived from the Italian translation of Wilkins’ ‘universal measure’, which was done by the Italian architect Tito Livio Burattini. The translation, ‘metro cattolico’, was used by him in a book that he published in 1675 on the same subject.

The Italian word metro, which then became mètre in France and meter in England, is derived from the Greek word metron, which translates to measure.

Decimal metric system

The three parts of the metric system described above were first used together in the 1780s and were referred to as the ‘système métrique décimal’.

Benjamin Franklin and Thomas Jefferson from the USA, Sir John Riggs-Miller from England, and Talleyrand and Condorcet from France, often met during the 1780s to discuss the implementation of a ‘universal measure’.

During these talks, they would discuss incorporating a decimal measurement and decimal currency and how to equalize weights and measures across all three nations. Together, they spoke in the French language, hence why the idea was referred to as système métrique décimal and not the decimal metric system.

The big breakthrough was in 1790, following the French Revolution, when these various ideas of a ‘universal measure’ culminated in the creation of the official decimal metric system.

Leading up to that year, at Talleyrand’s suggestion, French National Assembly commissioned French scientists to work diligently on a system of measurement using metric units. They looked to create the standard of weights and measurements as a base unit of length based on the Earth’s circumference. The system would be based on decimal numbers, with larger and smaller multiples of each unit being able to be multiplied and divided by ten and its powers. This was achieved in 1790, thus creating the metric system.

Shortly after that, Thomas Jefferson successfully implemented the world’s first decimal currency in the USA, with one dollar consisting of 100 cents. The creation and use of the decimal metric system, combined with the success of a decimal currency in the USA, resulted in the French government officially adopting the metric standards in 1795.

The subsequent success of the early decimal metric system in France encouraged other nations and governments to adopt the approach as it slowly spread throughout the world.

How many countries use the metric system?

The metric system is the preferred system of measurement in almost all countries worldwide. Although the United States was pivotal in its creation, they are one of the few countries in the world that do not officially use it.

USA, Myanmar, and Liberia are the only three countries in the world that use the imperial system as opposed to the metric system. The USA even has its own version of the imperial system known as the US customary units. Still, the country incorporates some metric measurements in their day-to-day use – e.g., they use kilometres for distance as opposed to miles.

What are the basic units and prefixes of the metric system?

The benefit of the metric system is that quantities of basic units are expressed using a prefix. This prefix outlines a multiple or submultiple of the unit, making it incredibly straightforward to determine exact quantities. Also, each prefix has a unique symbol to avoid confusion.

Base Units

MeasurementUnitSymbol
Lengthmeterm
Areasquare metersquare m, or m2
Areaare (100 square meters)a
Volumecubic metercubic m, or m3
Volumestere (1 cubic meter)s
Weightgramg
Weightmetric ton (1,000,000 grams)t
Capacityliterl
Temperaturedegree Celsius°C

Prefixes

PrefixSymbolFactor by which the base unit is multipliedName
Larger quantities or whole unitsyotta-Y1024Septillion
zeta-Z1021Sextillion
exa-E1018Quintillion
peta-P1015Quadrillion
tera-T1012Trillion
giga-G109Billion
mega-M106Million
kilo-k103Thousand
hecto-, hect-h102Hundred
deca-, dec-da101Ten

100
One
Smaller quantities or sub-unitsdeci-d10−1Tenth
centi-, cent-c10−2Hundredth
milli-m10−3Thousandth
micro-, micr-μ10−6Millionth
nano-n10−9Billionth
pico-p10−12Trillionth
femto-f10−15Quadrillionth
atto-a10−18Quintillionth
zepto-z10−21Sextillionth
yocto-y10−24Septillionth

Final thoughts

The metric system was invented by French scientists in the 18th century. However, the core principles that make up the measurement system have been discussed since as early as 1585.

After two centuries of ideation, a universal system materialized when in 1790, the decimal metric system was created in France. Since then, the metric system has been adopted by almost all nations in the world and is the preferred system of measurement in science.