# Inches to centimeters converter

> Convert inches to centimeters (inches to cm) with the exact factor, a conversion chart and worked steps.

Interactive version: https://www.calcopenly.com/conversion/inches-to-cm
Subject: Unit converters

Inch dimensions on a product listing may include fractions such as a half or a quarter. Enter a decimal or fraction for the full inch measurement before converting. Do not read 5 feet 6 inches as 5.6 inches, or confuse a screen's diagonal with its width.

One inch is exactly 2.54 centimeters, so 12 in is 30.48 cm. To convert inches to cm, multiply by 2.54; to convert back, multiply by 0.3937007874.

The international inch is defined as exactly 25.4 mm (1959 international yard and pound agreement). Because both units are defined exactly, the factor above is exact and the results here carry no conversion error.

## Inputs

- **Inches (in)**

## Results

- Centimeters (cm) — main result
- Conversion
- 1 cm in inches (in)

## Formula

$$
\text{centimeters} = \text{inches} \times 2.54
$$

## Worked examples

### 12 in to cm

- Inches (in): 12 in
- **Centimeters: 30.48 cm**
- Checked against: Exact-fraction computation from the legal unit definitions (scripts/gen-pairs.py, Python fractions)

### 2 in to cm

- Inches (in): 2 in
- **Centimeters: 5.08 cm**
- Checked against: Exact-fraction computation from the legal unit definitions (scripts/gen-pairs.py, Python fractions)

### 48 in to cm

- Inches (in): 48 in
- **Centimeters: 121.92 cm**
- Checked against: Exact-fraction computation from the legal unit definitions (scripts/gen-pairs.py, Python fractions)

## Questions

### When would I convert inches to cm?

Inch dimensions on a product listing may include fractions such as a half or a quarter. Enter a decimal or fraction for the full inch measurement before converting. Do not read 5 feet 6 inches as 5.6 inches, or confuse a screen's diagonal with its width.

### How many centimeters are in a inch?

One inch is exactly 2.54 centimeters. The international inch is defined as exactly 25.4 mm (1959 international yard and pound agreement).

### How do you convert inches to cm?

Multiply the number of inches by 2.54. For example, 12 in × 2.54 = 30.48 cm. To go the other way, divide by 2.54.

### How can I estimate inches to cm without a calculator?

Multiply by 2.5. That is 1.6% low of the exact factor 2.54, so 12 in comes out as 30 cm instead of 30.48.

### How accurate is the inches to centimeters converter?

Accuracy depends on your inputs and the method's assumptions. Decimal arithmetic uses 50 significant digits, but estimates, numerical methods and source data can be less precise; the displayed rounding does not remove those limits. It is checked against 3 worked examples whose answers come from independent sources; for example, “12 in to cm” is checked against Exact-fraction computation from the legal unit definitions (scripts/gen-pairs.py, Python fractions).

### Where does the method come from?

NIST SP 811 (2008), Guide for the Use of the International System of Units, Appendix B; NIST Handbook 44, Appendix C: General tables of units of measurement; BIPM, The International System of Units (SI Brochure), 9th edition.

## Sources

- [NIST SP 811 (2008), Guide for the Use of the International System of Units, Appendix B](https://www.nist.gov/pml/special-publication-811)
- [NIST Handbook 44, Appendix C: General tables of units of measurement](https://www.nist.gov/pml/weights-and-measures/publications/nist-handbooks/handbook-44)
- [BIPM, The International System of Units (SI Brochure), 9th edition](https://www.bipm.org/en/publications/si-brochure)