# Appendix I: Metric Conversion

All units of length in the metric system are derived from the meter. Although not a commonly used unit of measure in engineering, the meter is included here to show place value. Prefixes to the basic unit denote unit length. For example, the prefix cent- signifies one-hundredth; therefore, one centimeter is one one-hundredth of a meter.

 kilo =1,000 1 kilometer (km) = 1,000 meters (m)hecto=100 1 hectometer (hm) = 100 mDeca = 10 1 decameter (dam) = 10 m1 meter (m) = 1 mdeci = 0.1 1 decimeter (dm) = 0.1 mcenti = 0.01 1 centimeter (cm) = 0.01 mmilli = 0.001 1 millimeter (mm) = 0.001 mmicro = 0.000001 1 micrometer (micron) = 0.000001 m

Conversion between units of length in the metric system involves moving the decimal point to the right or to the left. Listing the units in order from largest to smallest will indicate how many places to move the decimal point and in which direction.

• To convert 4,200 cm to m, write the metric units in order, from largest to smallest.
km hm dam m dm cm mm __ __ micron

Because centimeters are two places to the right of meters, converting cm to m requires moving two decimal positions left; therefore, 4,200 cm = 42.00 m.

• To convert 5.0 microns to mm, list the metric units in order, from largest to smallest.
Km hm dam m dm cm mm __ __ micron

Because microns are three positions to the right of millimeters, converting micron to mm requires moving the decimal point three places left; therefore, 5.0 microns = .005 mm.

### Measures of Length

 10 millimeters (mm) = 1 centimeter (cm)10 centimeters = 1 decimeter (dm)10 decimeters = 1 meter (m)1,000 meters = 1 kilometer (km)

### Metric and English Conversion Table Linear Measure

 1 meter = 39.37 inches 1 yard = 0.9144 meter3.2808 feet 1 foot = 0.3048 meter1.0936 yards 1 foot = 304.8 millimeters1 centimeter = 0.3937 inch 1 inch = 2.54 centimeters1 millimeter = 0.03937 1 inch = 25.4 millimeters1 micron = 0.00003937 inch

To convert from mm to inches; divide the millimeters by 25.4.
Example: mm = 21.6535 in.
Or multiply by .03937; 550 mm x .003937 = 21.6535 in.

To convert from in. to mm, multiply the in. by 25.4.
Example: .750 x 25.4 = 19.05 mm.
Or divide by .03937:
Example: .750 in. divided by .03937 = 19.05 mm.