To convert centimeters to kilometers (cm to km), multiply by 0.00001. 1 centimeter equals 0.00001 km, about 1.7 times as much as a grain of rice.
| centimeters | kilometers |
|---|---|
| 1 centimeter | 0.00001 km |
| 2 centimeters | 0.00002 km |
| 5 centimeters | 0.00005 km |
| 10 centimeters | 0.0001 km |
| 25 centimeters | 0.00025 km |
| 50 centimeters | 0.0005 km |
| 100 centimeters | 0.001 km |
| 250 centimeters | 0.0025 km |
| 500 centimeters | 0.005 km |
| 1000 centimeters | 0.01 km |
Definition: 1/100 of a meter - the "centi" prefix doing the same job it does in "century" or "cent."
History: Introduced alongside the meter itself during the French Revolution's metric overhaul, the centimeter was designed from the start to be a convenient, everyday-sized subdivision - a meter is often too big and a millimeter too small for describing things like a person's height or a book's thickness.
Current use: Height, everyday object sizes, and fabric measurements across most of the world; also the standard unit doctors use internationally for body measurements.
Definition: A kilometer is 1,000 meters - the "kilo" doing the same job it does in kilogram or kilobyte.
History: The meter itself was originally defined, back in 1793 during the French Revolution, as one ten-millionth of the distance from the North Pole to the equator. Today it's defined by how far light travels in a tiny fraction of a second instead - a far more precise anchor - but either way, a kilometer has always just meant a thousand of whatever "one meter" happens to be.
Current use: Nearly everywhere on Earth measures road distances, race lengths, and everyday travel in kilometers. The US remains one of the few holdouts still measuring road trips in miles.