The metric system is based on the meter, which, according to the U.S. Coast and Geodetic Survey Reoprt of 1884, is equal to 39.370432 inches. The value commonly used is 39.37 inches, and is authorized by the U.S. goverment. The meter is defined as one ten-millionth the distance from the pole to the equator, measured on the meridian passing near Paris.

There are three principal units-the meter, the liter (pronounced lee-ter), and the gram, the units of length, capacity, and weight, respectively. Multiples of these units are obtained by prefixing to the names of the principal units the Greek words deca (10), hecto (100), and Kilo (1,000); the submultiples, or divisions, are obtained by prefixing the Latin words deci (1/10), centi (1/100) and milli (1/1000). The prefixes form the key to the entire system. In the following tables, the abbreviations of the principal units of these submultiples begin with a capital letter; they should always be written as here printed.