# cm to km Converter URL: https://speedycalculator.com/calculators/conversion/cm-to-km/ Last updated: 2026-10-25 > Convert centimetres (cm) to kilometres (km): 1 centimetre = 1 × 10^-5 km, so multiply by 1 × 10^-5 or divide by 100,000. Both fields are editable, so you can also type in kilometres and get centimetres back. ## Inputs - Centimetres (cm) ## Results - Kilometres ## Formula ``` 1 cm = 1 × 10^-5 km 1 km = 100,000 cm km = cm × 1 × 10^-5 ``` ## Explanation 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 CentimetresKilometresKilometresCentimetres1 cm1 × 10-5 km1 km100,000 cm10 cm0.0001 km2 km200,000 cm100 cm0.001 km5 km500,000 cm1,000 cm0.01 km10 km1,000,000 cm10,000 cm0.1 km20 km2,000,000 cm50,000 cm0.5 km50 km5,000,000 cm100,000 cm1 km100 km10,000,000 cm1,000,000 cm10 km1,000 km100,000,000 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). ## Worked example Inputs — Centimetres: 100,000 cm. Results — **Kilometres = 1 km**. ## FAQ **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. ## Sources - [NIST Special Publication 811 – Guide for the Use of the International System of Units](https://www.nist.gov/pml/special-publication-811) - [NIST Handbook 44 Appendix C – General tables of units of measurement](https://www.nist.gov/pml/owm/nist-handbook-44-current-edition)