Before 1790, measurement was a chaotic mess. A "foot" in Paris was different from a "foot" in London or Rome. Merchants were cheated, scientists couldn't compare data, and tax collectors were confused. It took the French Revolution to fix it.
1790: "For All People, For All Time"
In the midst of the revolution, the French Academy of Sciences set out to create a system based on nature, not royal decree. They defined the Meter (from Greek metron, meaning measure) as:
This definition meant that the meter belonged to the Earth itself, making it universal.
The Platinum Archives
Since measuring the Earth every time you needed a ruler was impractical, the French cast a standard bar made of pure platinum. This bar, placed in the Archives de la République in 1799, became the physical embodiment of the meter for nearly a century.
From this length, they derived everything else:
- Liter (Volume): A cube with sides of 1/10th of a meter.
- Gram (Mass): The weight of a cubic centimeter of water at freezing point.
1960: The Birth of SI
As science advanced, physical objects (which can scratch or expand) weren't precise enough. In 1960, the metric system was rebranded as the International System of Units (SI). Definitions shifted from physical objects to universal constants.
Why the US is the Outlier
Only three countries in the world have not officially adopted the metric system: Liberia, Myanmar, and the United States. In the US, high costs of industrial retooling and cultural resistance kept the "Imperial" system alive, although US scientists and military use metric almost exclusively.
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