# How do I convert inches to cm?

Converts inches (in) to centimeters (cm) and back, with the exact unit definitions.

- Page: https://www.acalculator.org/convert/inches-to-cm
- JSON spec: https://www.acalculator.org/convert/inches-to-cm.json
- Version: 9339b54b4d7b

## Default answer

Example with the default inputs (Inches (in) 1): 1 in = 2.54 cm.

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| value | Inches (in) | The amount in inches to convert. |
| result | Centimeters (cm) | The same amount in centimeters. |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| value | Inches (in) | The amount in inches to convert. |
| result | Centimeters (cm) | The amount in centimeters. |

## Method

cm = in × 2.54

## Assumptions

- 1 inch = 2.54 centimeters, from the exact definitions in NIST SP 811.
- The answer shows at most 6 decimal places; the calculation keeps full precision.

## Worked examples

1. value = 1 gives result = 2.54. Source: exact unit definitions in NIST SP 811 (2008), Appendix B.8.
2. value = 12 gives result = 30.48. Source: exact unit definitions in NIST SP 811 (2008), Appendix B.8.
3. result = 30.48 gives value = 12. Source: exact unit definitions in NIST SP 811 (2008), Appendix B.8.

## FAQ

### How many centimeters are in an inch?

1 inch is 2.54 centimeters, from the exact unit definitions (NIST SP 811).

### How do I convert inches to cm?

Multiply by 2.54: cm = in × 2.54. For example, 1 in × 2.54 = 2.54 cm.

### How do I convert cm back to inches?

Multiply by 0.393701, or type the centimeters into the second box and the converter works it out. 1 centimeter is 0.393701 inches.

## Sources

- NIST SP 811 (2008), Guide for the Use of the International System of Units, Appendix B.8. https://www.nist.gov/pml/special-publication-811