A metric scale is a form of measurement used in the metric system. The metric system is the world standard for measurement and is made of three basic units: the meter, gram and liter. The meter measures length, the gram measures mass and the liter measures volume.
The metric system follows the idea that base units become larger or smaller based on the power of 10. The base units have prefixes to define these larger and smaller units. For example, 1 kilometer is equal to 1,000 meters. One centimeter is one-hundredth of a meter, and 1 millimeter is 1,000 times smaller than a meter.