Centimeters to Kilometers

The most practical use of this pair is map scale. A scale of 1:100,000 means one centimeter on the map stands for 100,000 cm on the ground, which is exactly one kilometer. On a 1:50,000 topographic sheet, one centimeter is 50,000 cm, or 0.5 km, and on a 1:25,000 hiking map it is 25,000 cm, or 0.25 km, so four centimeters make a kilometer.

To measure a route, lay a ruler or a piece of string along it, read the length in centimeters, multiply by the scale number and divide by 100,000. A trail that measures 7.3 cm on a 1:50,000 map is 7.3 × 50,000 = 365,000 cm, which is 3.65 km. Remember that this is the horizontal distance; steep ground adds real walking distance the map does not show.

Both units belong to the metric system, which France introduced in the 1790s so that every step between units would be a power of ten. Centi comes from the Latin for hundred and marks a hundredth; kilo comes from the Greek for thousand. A kilometer is 1,000 meters and a meter is 100 centimeters, so a kilometer is 1,000 × 100 = 100,000 cm, or 10⁵ cm.

Because no odd factor is involved, nothing has to be rounded. The meter behind both units has been defined by the speed of light since 1983, so a kilometer and a centimeter are exactly related by definition.

The usual mistake is dividing by 1,000 because the word kilo suggests it. That converts meters to kilometers, not centimeters, and gives an answer 100 times too large: 5,000 cm would come out as 5 km instead of 0.05 km. Count the five zeros, or go through meters: divide by 100, then by 1,000.

For the opposite direction, see kilometers to centimeters. Other metric and imperial lengths are listed in the unit converter.