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What is a Centimeter?

Kathryn Pless
Kathryn Pless

A centimeter, sometimes also written “centimetre” or abbreviated "cm," is a unit of measurement in the metric system that is equal to one hundredth of a meter. Accordingly, there are exactly 100 centimeters per meter. The metric system is also known as the International System of Units, and its main goal is to guide the way in which weights and measures are calculated . Most countries have adopted it. Some countries, including the United States, use primarily the imperial system, which is different; where the metric system is based on units of 10, the imperial system is based on units of 12. The metric system is also the standard system of measurement within the scientific community, even in countries that use primarily imperial calculations. This is particularly true in physics and electromagnetic contexts. These disciplines have traditionally used what is known as the “centimetre-gram-second” system of units as a way of being streamlined.

The Metric System Generally

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Scientist with beakers

Throughout most of the world the metric system has been the dominant system of quantification for centuries. In 1795, the French Academy of Sciences developed it to standardize measurements in France. Before this standardization, measurements varied from area to area, sometimes wildly. In 1875, the “Treaty of the Meter” was signed at the International Bureau of Weights and Measurements conference. Since that time the metric system has been adopted by the vast majority of countries around the world, and is used commonly even in those that haven’t officially mandated its use.

Metric measurements operate on a system of 10s. Distance is typically measured in relation to the meter. A kilometer, for instance, is 1,000 meters, while a millimeter is one 1,000th. The prefix “cent-” means 100, and as such there are 100 centimeters in a meter.

Use Within the Scientific Community

The scientific community uses the International System of Units (SI), which is usually understood to be a modern form of the metric system. Having one standardized system enables scientists from different countries and regions to duplicate research and gather data. Science classrooms and school curricula typically use metric measurements as a result, even in places where these are not the standard units in larger society.

Imperial Conversions

The United States is the largest and best known country to have resisted standardizing to the metric system. It uses instead the imperial system, which was originally designed in Great Britain. The system operates on units of 12, with the foot, the yard, and the mile being the primary measurements of length. There are 12 inches in a foot and 36 in a yard, for instance, and 63,360 inches per mile.

One centimeter is equal to 0.4 inches. Conversion to inches is achieved by multiplying the smaller unit by 0.39. Distance normally is measured in meters so that one mile would be the equivalent of 1.6 kilometers, or about 160,000 centimetres.

Great Britain adopted the metric system in 1965. The United States government passed the Omnibus Trade and Competitive Act in 1988 that required the federal government to adopt the metric system by 1992, but the imperial system is still the preferred system used in private industry and in schools.

CGS Systems

This tiny unit of measurement is also at the core of what’s known as the “centimetre-gram-second” (CGS) system of documentation. This system was once very popularly used in the professional physics discipline, particularly where electromagnetic measurements and readings were concerned. It captured both length, mass, and time, and combined the three in an easy-to-understand format. This system is still used in some labs, but in most places it has been replaced with the similar meter-kilogram-second (MKS) system, which is more adaptable to larger measurements.

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Discussion Comments


@Markerrag -- I think the metric system hasn't caught on in the United States for at least three reasons. First, we think of measurements in terms of imperial standards. We are inclined to think of distances in miles, inches, feet and yards rather than kilometers, centimeters, decameters and meters. Similarly, we think of gallons instead of liters when it comes to liquid measurements, and how hard would it be to translate recipes from imperial to metric?

Second, imagine the cost of converting to metric. Think of just a car and converting filling stations from gallons to liters. Think of drivers dealing with kilometers instead of miles (if the speed limit is 70 miles per hour, what does that mean in kilometers?)

Finally, who wants to be the first generation to make the transition from imperial to metric? Once the metric system is learned, it is easy but a lot of adjustments would have to me made and the brunt of that would fall on one generation or the other. It could be that people like the metric system, but want to shift the burden of transitioning to it to another generation.


The metric system confuses me no end. I don't mean that it is hard to learn. I mean that we in the United States have refused to learn it.

The confusing thing is that it ought to come easy to us. Our money is based on tens, so how hard could it be to jump to that basis when considering measurements? We already use "metric money," so why not jump in with both feet like the rest of the world?

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