The basic metric units are meter (for length), gram (for mass or weight), and liter (for volume).

One unit can be converted into another one. For example, one milliliter equals one cubic centimeter and one gram is the weight of one cc of water.

To convert various prefixes and thus variously-sized units, we move up and down this list of prefixes, moving the decimal point as we go. This is the process of converting one unit to another.

1 milliliter = 0.1 centiliters

    = 0.01 deciliters
    = 0.001 liters
    = 0.000 1 dekaliters
    = 0.000 01 hectoliters
    = 0.000 001 kiloliters

Unit conversion is defined as the process of converting one unit to another. There are a number of metric prefixes involved in unit conversions:

Metric prefixes: kilo-, hecto-, deca-, deci-, centi- and milli-

The following sentence is used to remember the prefixes in order :

"King Henry Doesn't (Usually) Drink Chocolate Milk"

kilo- hecto- deca- (Unit)- deci- centi- milli-

The first letters of the words stand for the prefixes. "Usually" stands for Unit being meters, grams or liters.

Each step is ten times or one-tenth as much as the step on either side. So, we have:

1 kilometer = 10 hectometers

= 100 decameters
= 1000 meters
= 10,000 decimeters
= 100,000 centimeters
= 1,000,000 millimeters

Metric Prefix Common Unit Exponent Symbol
Kilo 1000 $10^{3}$ K
Hecto 100 $10^{2}$ H
Deka 10 $10^{1}$ D or Da
Base Unit 1 $10^{0}$ Meters, Grams or Liters
Deci 0.1 $10^{-1}$ d
Centi 0.01 $10^{-2}$ c
Milli 0.001 $10^{-3}$ m