The Metric System

Biology Class

What is the metric system?

  1. the decimal measuring system based on the meter, liter, and gram as units of length, capacity, and weight or mass. The system was first proposed by the French astronomer and mathematician Gabriel Mouton (1618–94) in 1670 and was standardized in France under the Republican government in the 1790s.

Nearly every country is using the metric system

The metric system in depth

The metric system provides units of measurement for distance, volume, mass, time, and temperature. It builds these units using a basic unit and a set of prefixes.

The following list shows five important basic units in the metric system.

The following table shows ten metric prefixes, with the three most commonly used in bold.

PrefixMeaningNumberPower of Ten

Giga-One billion1,000,000,000109

Mega-One million1,000,000106

Kilo-One thousand1,000103

Hecta-One hundred100102



Deci-One tenth0.110-1

Centi-One hundredth0.0110-2

Milli-One thousandth0.00110-3

Micro-One millionth0.00000110-6

Nano-One billionth0.00000000110-9

Large and small metric units are formed by linking a basic unit with a prefix. For example, linking the prefix kilo- to the basic unit meter gives you the kilometer, which means 1,000 meters. Similarly, linking the prefix milli- to the basic unit liter gives you the milliliter, which means 0.001 (one thousandth) of a liter.