Centimetres are the metric everyday unit, inches the U.S. and UK one for screens, clothing and tools. Since 1959 one inch is exactly 2.54 cm, so this conversion is exact rather than approximate.
How to use the cm to Inches Converter
- Type the number of centimetres into the Centimetres field. Decimals such as 15 are fine.
- Read the answer in Inches – it updates as you type, with no button to press.
- To convert the other way, type into Inches 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 ⇄ in. 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 0.39370079 inches. The calculator multiplies the number of centimetres you type by 0.39370079 to give inches, and when you type into the inches field it divides by the same factor to give centimetres. Because the ratio never changes, doubling the centimetres always doubles the inches. 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 inches
- Write down the value in centimetres, for example 30 cm.
- Multiply by the conversion factor 0.39370079 (because 1 centimetre = 0.39370079 in).
- 30 × 0.39370079 = 11.811024 in.
- To go back from inches to centimetres, divide by 0.39370079 – or multiply by 2.54.
cm to in conversion table
| Centimetres | Inches | Inches | Centimetres |
|---|---|---|---|
| 1 cm | 0.39370079 in | 1 in | 2.54 cm |
| 2 cm | 0.78740157 in | 2 in | 5.08 cm |
| 5 cm | 1.9685039 in | 5 in | 12.7 cm |
| 10 cm | 3.9370079 in | 10 in | 25.4 cm |
| 15 cm | 5.9055118 in | 20 in | 50.8 cm |
| 25 cm | 9.8425197 in | 50 in | 127 cm |
| 30 cm | 11.811024 in | 100 in | 254 cm |
| 50 cm | 19.685039 in | 1,000 in | 2,540 cm |
| 60 cm | 23.622047 in | ||
| 75 cm | 29.527559 in | ||
| 150 cm | 59.055118 in | ||
| 200 cm | 78.740157 in |
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 an inch?
The inch has been defined as exactly 25.4 mm since 1959. It is used in the U.S. for almost everything and worldwide for screen sizes, wheel and tyre sizes, pipe threads and many tools.
Quick mental conversion
For a fast estimate, multiply centimetres by about 0.39 to get inches; the error is about 0.9%. Use the calculator above when you need the exact figure.
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 = 0.39370079 in1 in = 2.54 cmin = cm × 0.39370079Worked example
Inputs — Centimetres: 30 cm.
Results — Inches = 11.81102362 in.
Frequently asked questions
How many inches is 30 cm?
About 11.81 in.
Why exactly 2.54?
The inch was defined as exactly 25.4 mm by the 1959 international agreement.
How do I convert centimetres to inches?
Multiply the number of centimetres by 0.39370079. For example, 30 cm × 0.39370079 = 11.811024 in.
How do I convert inches back to centimetres?
Divide by 0.39370079 (or multiply by 2.54), or simply type the value into the inches field above.
What is 10 cm in inches?
10 cm = 3.9370079 in.
What is 100 cm in inches?
100 cm = 39.370079 in.
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 inches. To pick any length unit, use the general length converter linked under Related calculators.
What formula does the cm to Inches Converter use?
1 cm = 0.39370079 in.