A kilometre is 100,000 centimetres, so divide by 10⁵. This is the conversion behind map scales: on a 1:100,000 map, 1 cm on paper is 1 km on the ground.
How to use the cm to km Converter
- Type the number of centimetres into the Centimetres field. Decimals such as 50,000 are fine.
- Read the answer in Kilometres – it updates as you type, with no button to press.
- To convert the other way, type into Kilometres and the centimetres are recalculated.
- Press Copy results to copy both values with the page title, or Copy link to share this exact conversion.
This page converts only cm ⇄ km. Need a different unit? Use the general length converter, where you can choose any “from” and “to” unit.
How it works
Both units measure length, so they are always in the same ratio: one centimetre equals 1 × 10^-5 kilometres. The calculator multiplies the number of centimetres you type by 1 × 10^-5 to give kilometres, and when you type into the kilometres field it divides by the same factor to give centimetres. Because the ratio never changes, doubling the centimetres always doubles the kilometres. Results are calculated at full precision and rounded only for display (up to eight decimal places, with very large or small values shown in scientific notation).
How to convert centimetres to kilometres
- Write down the value in centimetres, for example 100,000 cm.
- Multiply by the conversion factor 1 × 10-5 (because 1 centimetre = 1 × 10-5 km).
- 100,000 × 1 × 10-5 = 1 km.
- To go back from kilometres to centimetres, divide by 1 × 10-5 – or multiply by 100,000.
cm to km conversion table
| Centimetres | Kilometres | Kilometres | Centimetres |
|---|---|---|---|
| 1 cm | 1 × 10-5 km | 1 km | 100,000 cm |
| 10 cm | 0.0001 km | 2 km | 200,000 cm |
| 100 cm | 0.001 km | 5 km | 500,000 cm |
| 1,000 cm | 0.01 km | 10 km | 1,000,000 cm |
| 10,000 cm | 0.1 km | 20 km | 2,000,000 cm |
| 50,000 cm | 0.5 km | 50 km | 5,000,000 cm |
| 100,000 cm | 1 km | 100 km | 10,000,000 cm |
| 1,000,000 cm | 10 km | 1,000 km | 100,000,000 cm |
What is a centimetre?
A centimetre is one hundredth of a metre (10 mm). It is the everyday metric unit for body height, clothing, furniture and school rulers.
What is a kilometre?
A kilometre is 1,000 metres. It is the standard unit for road distances, maps, running races and travel in almost every country except the U.S. and UK, where miles are still used on road signs.
Common mistakes to avoid
Mixing the international foot (0.3048 m) with the old u.s. survey foot, confusing nautical and statute miles, and writing decimal feet such as 5.5 ft as “5 ft 5 in” (it is 5 ft 6 in).
Formula
1 cm = 1 × 10^-5 km1 km = 100,000 cmkm = cm × 1 × 10^-5Worked example
Inputs — Centimetres: 100,000 cm.
Results — Kilometres = 1 km.
Frequently asked questions
How many cm in a km?
100,000.
What is 1 cm on a 1:50,000 map?
0.5 km.
How do I convert centimetres to kilometres?
Multiply the number of centimetres by 1 × 10^-5. For example, 100,000 cm × 1 × 10^-5 = 1 km.
How do I convert kilometres back to centimetres?
Divide by 1 × 10^-5 (or multiply by 100,000), or simply type the value into the kilometres field above.
What is 10 cm in kilometres?
10 cm = 0.0001 km.
What is 100 cm in kilometres?
100 cm = 0.001 km.
Is this conversion exact?
Yes. The factor comes from the official definitions of both units (NIST and the SI), so the only difference you may see is rounding in the last displayed digit.
Can I convert to other units on this page?
This page converts only between centimetres and kilometres. To pick any length unit, use the general length converter linked under Related calculators.
What formula does the cm to km Converter use?
1 cm = 1 × 10^-5 km.