Metric

1 kilometer (km)=
1000 meters
100,000 centimeters
1,000,000 millimeters
0.539956 nautical mile
0.621371 mile
1093.61 yards
3280.83 feet
39,370.08 inches

1 meter (m) =
10 decimeters
100 centimeters
1000 millimeters
1.09361 yards
3.28084 feet
39.37008 inches

1 decimeter (dm) = 10 centimeters

1 centimeter (cm) =
0.01 meter
10 millimeters
0.0328 foot
0.3937 inch

1 millimeter (mm) =
0.001 meter
0.1 centimeter
1000 micron
0.03937 inch

1 micrometer or micron (μm) =
0.000001 meter = one millionth meter
0.0001 centimeter
0.001 millimeter
0.00003937 inch
39.37 micro-inches

Surveyors Measure

1 mile = 8 furlongs = 80 chains
1 furlong = 10 chains = 220 yards
1 chain =
    4 rods = 22 yards = 66 feet = 100 links
1 rod =
    5.5 yards = 16.5 feet = 25 links
    5.0292 meter
1 link = 7.92 inches
1 span = 9 inches
1 hand = 4 inches

US Customary

1 mile (mi) =
0.868976 nautical mile
1760 yards
5280 feet
63,360 inches
1.609344 kilometers
1609.344 meters
160,934.4 centimeters
1,609,344 millimeters

1 yard (yd)=
3 feet
36 inches
0.9144 meter
91.44 centimeter
914.4 millimeter

1 foot (international) (ft) =
12 inches = 1⁄3 yard
0.3048 meter
30.48 centimeter
304.8 millimeters

1 survey foot =
1.000002 international feet
12⁄39.37 = 0.3048006096012 meter

1 inch (in)=
1000 mils
1,000,000 micro-inch
2.54 centimeters
25.4 millimeters
25,400 microns

1 mil =
0.001 inch
1000 micro-inches
0.0254 millimeters

1 micro-inch (μin) =
0.000001 inch = one millionth inch
0.0254 micrometer (micron)

 Nautical Measure

1 league = 3 nautical miles
1 nautical mile =
   1.1508 statute miles
   6076.11549 feet
   1.8516 kilometers
1 fathom = 2 yards = 6 feet
1 knot = nautical unit of speed =
   1 nautical mile per hour
   1.1508 statute miles per hour
   1.8516 kilometers per hour