How to Convert Centimetres to Kilometres (cm to km)
Length conversions come up when reading overseas furniture specs, cycling the Round Island Route in kilometres while a foreign app shows miles, or checking marine distances in the Singapore Strait in nautical miles. This guide shows how to convert centimetres into kilometres by hand, with examples and a quick-reference table.
The conversion
To convert centimetres to kilometres, multiply the value by 1.000000e-05. To go the other way, divide by the same number (or multiply by 100,000). Because the factor is tiny, scientific notation keeps the numbers manageable.
Kilometres = centimetres × 1.000000e-05
Worked examples
- 3 cm = 3.000000e-5 km
- 12.5 cm = 0.000125 km
- 75 cm = 0.00075 km
Centimetres to Kilometres table
| Centimetres | Kilometres |
|---|---|
| 1 cm | 1.000000e-5 km |
| 2 cm | 2.000000e-5 km |
| 5 cm | 5.000000e-5 km |
| 10 cm | 0.0001 km |
| 20 cm | 0.0002 km |
| 25 cm | 0.00025 km |
| 50 cm | 0.0005 km |
| 100 cm | 0.001 km |
| 250 cm | 0.0025 km |
| 500 cm | 0.005 km |
| 1,000 cm | 0.01 km |
Common questions
Is cm to km exact?
The factors used here are the internationally defined values where they exist; results are rounded for display only.
How do I convert back?
Use the Kilometres to Centimetres converter.
Mistakes to avoid
Multiplying when you should divide
Converting to a smaller unit gives a bigger number, and converting to a larger unit gives a smaller one. If your answer moves the wrong way, you have inverted the factor.
Mixing similar-sounding units
US and imperial gallons, pints and tons are different sizes, and decimal kilobytes differ from binary kibibytes.
Forgetting squared and cubed units
Area and volume factors are the length factor squared or cubed, so 1 m² is about 10.76 sq ft, not 3.28.
Background
Singapore adopted the metric system in the 1970s, replacing imperial units and traditional Chinese measures in most official uses. Metric units are now standard in schools, trade and government, but older units survive in property, markets and imported goods.
Writing the units next to every number while you work is the simplest way to avoid mistakes. If the units do not cancel to leave the one you want, the calculation is set up wrongly.
Unit conversion is simply multiplication by a fixed ratio. The ratio between two units of the same quantity never changes, so once you know it you can convert any value in either direction.
For any value, use the Centimetres to Kilometres Converter or browse all length converters.
Run your own numbers: Centimetres to Kilometres Converter