# cm to Inches Converter

URL: https://speedycalculator.com/calculators/conversion/cm-to-inches/
Last updated: 2026-10-25

> Convert centimetres (cm) to inches (in): 1 centimetre = 0.39370079 in, so multiply by 0.39370079 or divide by 2.54. Both fields are editable, so you can also type in inches and get centimetres back.

## Inputs

- Centimetres (cm)

## Results

- Inches

## Formula

```
1 cm = 0.39370079 in
1 in = 2.54 cm
in = cm × 0.39370079
```

## Explanation

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

CentimetresInchesInchesCentimetres1 cm0.39370079 in1 in2.54 cm2 cm0.78740157 in2 in5.08 cm5 cm1.9685039 in5 in12.7 cm10 cm3.9370079 in10 in25.4 cm15 cm5.9055118 in20 in50.8 cm25 cm9.8425197 in50 in127 cm30 cm11.811024 in100 in254 cm50 cm19.685039 in1,000 in2,540 cm60 cm23.622047 in75 cm29.527559 in150 cm59.055118 in200 cm78.740157 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).

## Worked example

Inputs — Centimetres: 30 cm.

Results — **Inches = 11.81102362 in**.

## FAQ

**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.


## 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)