How to Convert Kilometres to Centimetres (km to cm)
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 kilometres into centimetres by hand, with examples and a quick-reference table.
The conversion
To convert kilometres to centimetres, multiply the value by 100,000. To go the other way, divide by the same number (or multiply by 1.000000e-05). For a quick estimate, multiply by about 100,000.
Centimetres = kilometres × 100,000
Worked examples
- 3 km = 300,000 cm
- 12.5 km = 1,250,000 cm
- 75 km = 7,500,000 cm
Kilometres to Centimetres table
| Kilometres | Centimetres |
|---|---|
| 1 km | 100,000 cm |
| 2 km | 200,000 cm |
| 5 km | 500,000 cm |
| 10 km | 1,000,000 cm |
| 20 km | 2,000,000 cm |
| 25 km | 2,500,000 cm |
| 50 km | 5,000,000 cm |
| 100 km | 10,000,000 cm |
| 250 km | 25,000,000 cm |
| 500 km | 50,000,000 cm |
| 1,000 km | 100,000,000 cm |
Common questions
Is km to cm 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 Centimetres to Kilometres converter.
Mistakes to avoid
Rounding the factor too early
Using 3 instead of 3.28 for feet per metre introduces an error of almost 9% before you have started.
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.
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.
Background
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.
For everyday use, three or four significant figures are usually enough. Engineering, science and trade documents may need more, and rounding should happen only at the end of a calculation.
Many conversion factors are exact by definition. The inch has been defined as exactly 2.54 centimetres since 1959, and the pound as exactly 0.45359237 kilograms, so conversions involving them can be as precise as you need.
For any value, use the Kilometres to Centimetres Converter or browse all length converters.
Run your own numbers: Kilometres to Centimetres Converter