Celebrating 150 Years of Measurement
On May 20, 1875, an international conference called the Metre Convention created the International Bureau of Weights and Measures (in French, the Bureau International des Poids et Mesures, or BIPM). The aim of the BIPM is to help countries agree on a common worldwide standard for how things are measured.
The 1875 conference was held in the city of Paris, France, and the treaty was signed by 17 nations, including Germany, Russia, Brazil, and the then 108-year-old United States of America. In 2025 , the BIPM will mark this anniversary with .
The meter is the standard unit of length. In most English-speaking nations, meter is spelled metre鈥攖he main exception is the United States. The same spelling difference applies to other units based on the meter, such as the kilometer (1000 meters) and the millimeter (0.001 meters).
Everyday Uses of the Meter in the USA
In the United States 鈥攁nd, to a lesser extent, in the United Kingdom 鈥攑eople generally use inches, feet, yards, and miles to talk about distances (1 yard is exactly 0.9144 meters). However, in the area of science and technology, meters are routinely used.
There are other areas where the meter is part of day-to-day life in the USA. Here are four examples.
- The US military measures distances in klicks, where one klick is equal to one kilometer (about 0.62 miles). Military personnel use the abbreviation klick because it鈥檚 shorter and clearer for messages sent by radio.
- In healthcare, blood pressure is measured in millimeters of mercury (mmHg). One mmHg is equivalent to the pressure exerted by a column of mercury that is one millimeter (about 0.04 inches) high.
- In the world of movies and photography, the most common film format is 35 millimeters (35 mm). For this, we can thank the legendary American inventor Thomas Edison, who used film that was 35 mm (about 1.38 inches) wide on a motion picture exhibition device he unveiled in New York in 1894.
- Athletes and fitness enthusiasts run distances measured in meters, from the 100-meter sprint, to the many 5K and 10K events held around the country. 5K means 5 kilometers (about 3.1 miles); 10K means 10 kilometers (about 6.2 miles).
A Unit Born from the Earth
The meter wasn鈥檛 plucked from thin air. In the late 18th century, after the French Revolution, scientists proposed a new, universal unit of length: one ten-millionth of the distance from the equator to the North Pole, along a meridian passing through Paris.
Rooted in the natural world, the meter was elegant and logical, and it formed the basis of the metric system. But it was also nearly impossible to measure accurately. The first prototype, forged in platinum in 1799, was based on calculations with notable errors.
By the time the Metre Convention was signed in 1875, the world needed something better. Enter the International Prototype Metre鈥攁 carefully crafted bar of platinum-iridium, stored in a vault near Paris. It became the global benchmark for length.
Earth to Cosmos
But as science advanced, so did the need for something even more reliable. Eventually, in 1983, the meter was redefined, not by a physical object, but by a universal constant: the speed of light. Today鈥檚 meter is the distance light travels in a vacuum in exactly 1/299,792,458 of a second.
That shift鈥攆rom the size and shape of the Earth to the speed of light鈥攊s more than technical trivia. It mirrors a bigger transformation: from looking down at our planet to looking up at the stars.
Want to celebrate the meter? May 20 is , which celebrates and inspires discussions about the importance of accurate measurements in our interconnected world.