The Metric System

Most of the world uses the metric system. The only countries not on this system are Liberia, Burma (Myanmar), and the United States of America. The metric system is based on 10s (tens). For example, 10 millimeters make 1 centimeter, 10 centimeters make 1 decimeter, and 10 decimeters make a meter.

Units smaller than a meter have Latin prefixes:

  • deci – means 10th (tenth); 10 decimeters make a meter.
  • centi- means 100th (hundredth); 100 centimeters make a meter.
  • milli- means 1,000th (thousandth); 1,000 millimeters make a meter.

Units larger than a meter have Greek prefixes:

  • deka- means 10; a dekameter is 10 meters.
  • hecto- means 100; a hectometer is 100 meters.
  • kilo- means 1,000; a kilometer is 1,000 meters.

Examples of the Metric System

Unit Value
kilometer (km) 1,000 meters
hectometer (hm) 100 meters
dekameter (dam or dkm) 10 meters
meter (m) 1 meter
decimeter (dm) 0.1 meter
centimeter (cm) 0.01 meter
millimeter (mm) 0.001 meter
Unit Value
kiloliter (kl) 1,000 liters
hectoliter (hl) 100 liters
dekaliter (dal or dkl) 10 liters
liter (l) 1 liter
deciliter (dl) 0.1 liter
centiliter (cl) 0.01 liter
milliliter (ml) 0.001 liter

In the field of atmospheric science, even smaller measures must be used for lengths such as the diameter of a raindrop or aerosol particle, and capacities such as the volume of a pollutant:
  • micro – means 1,000,000th (or one millionth); a million microns, or micrometers, make a meter
  • nano – means 1,000,000,000th (or one billionth); a billion nanometers make a meter
Unit Value
micrometer (um) 0.000001 meters
nanometer (nm) 0.000000001 meters
Unit Value
microliter 0.000001 liters
nanoliter 0.000000001 liters

For an explanation of data volumes, please visit our Data Volume Page

Other Useful Metric Conversions

Multiply By To Find
centimeters 0.0328 feet
centimeters 0.3937 inches
Feet 30.4801 centimeters
Inches 2.54 centimeters
Inches 0.0833 feet
Yards 91.44 centimeters
Yards 0.9144 meters
kilometers 3,280.833 feet
kilometers 0.6214 miles
kilometers/hour 0.6214 miles/hour
Knots 1.8532 kilometers/hour
meters 3.2808 feet
meters 39.37 inches
meters 1.0936 yards
Miles 1.6093 kilometers
Miles/hour 0.8684 knots
Miles/hour 1.6093 kilometers/hour
Miles/hour 0.447 meters/second
grams 0.0353 ounces
grams 0.0022 pounds
kilograms 2.2046 pounds
Ounces 28.3495 grams
Pounds 453.5924 grams
Pounds 0.4536 kilograms
liters 1.0567 quarts
Quarts 0.946 liters
Gallons 3.7853 liters