# Inches to Centimeters (in to cm)

> Convert inches to centimeters: 1 in = 2.54 cm. Exact conversion factor, formula, 22-row table and worked examples, with JSON API and MCP access.

- Page id: `inches-to-cm` · Quantity: Length (`length`, base unit m) · Tool: `convert_units`
- Canonical page: https://tttkmbb.com/conversion/inches-to-cm · This document: https://tttkmbb.com/conversion/inches-to-cm.md · JSON: https://tttkmbb.com/conversion/inches-to-cm.json (add `?value=` for a result)

## Formula

- `1 in = 2.54 cm`
- `centimeters = inches × 2.54`
- Reverse: `inches = centimeters × 0.3937007874`

The factor follows from the SI definitions of both units (NIST SP 811); values below are rounded to 6 significant figures, the API returns up to 12.

## Worked examples

- 5 in = 12.7 cm
- 12.5 in = 31.75 cm
- 100 in = 254 cm

## Conversion table

| Inches (in) | Centimeters (cm) |
| --- | --- |
| 1 | 2.54 |
| 2 | 5.08 |
| 3 | 7.62 |
| 4 | 10.16 |
| 5 | 12.7 |
| 6 | 15.24 |
| 7 | 17.78 |
| 8 | 20.32 |
| 9 | 22.86 |
| 10 | 25.4 |
| 15 | 38.1 |
| 20 | 50.8 |
| 25 | 63.5 |
| 30 | 76.2 |
| 40 | 101.6 |
| 50 | 127 |
| 75 | 190.5 |
| 100 | 254 |
| 200 | 508 |
| 250 | 635 |
| 500 | 1270 |
| 1000 | 2540 |

## API

- `GET https://tttkmbb.com/api/v1/convert?value=5&from_unit=in&to_unit=cm` → unified JSON envelope with `result.values.result`, `formula`, `factor`, `sources`, `freshness`
- MCP: server `https://tttkmbb.com/mcp`, tool `convert_units` with `{"value":5,"from_unit":"in","to_unit":"cm"}`
- All length units: https://tttkmbb.com/api/v1/units?quantity=length · full converter: [Length Converter](https://tttkmbb.com/conversion/length.md)
- Authentication: none. Freshness: `static` (fixed conversion factors).

## FAQ

**How many centimeters are in one inch?**

1 in = 2.54 cm. The factor comes from the SI definitions of both units (NIST SP 811 / BIPM), so it is exact or correct to at least 10 significant figures.

**What is the formula to convert inches to centimeters?**

Multiply the value in inches by 2.54: centimeters = inches × 2.54. For example, 5 in = 12.7 cm.

**How do I convert centimeters back to inches?**

Multiply by the inverse factor 0.3937007874 (inches = centimeters × 0.3937007874), or use the centimeters-to-inches page.

## Related conversions

- [Centimeters to inches](https://tttkmbb.com/conversion/cm-to-inches.md) (reverse)
- [Kilometers to Miles](https://tttkmbb.com/conversion/km-to-miles.md)
- [Miles to Kilometers](https://tttkmbb.com/conversion/miles-to-km.md)
- [Meters to Feet](https://tttkmbb.com/conversion/meters-to-feet.md)
- [Feet to Meters](https://tttkmbb.com/conversion/feet-to-meters.md)
- [Millimeters to Inches](https://tttkmbb.com/conversion/mm-to-inches.md)
- [Inches to Millimeters](https://tttkmbb.com/conversion/inches-to-mm.md)
- [Meters to Yards](https://tttkmbb.com/conversion/meters-to-yards.md)
- [Yards to Meters](https://tttkmbb.com/conversion/yards-to-meters.md)

## Data Sources

- NIST Special Publication 811 – Guide for the Use of the International System of Units (SI), Appendix B conversion factors — https://www.nist.gov/pml/special-publication-811 (standard, retrieved 2026-09-24)
- BIPM – The International System of Units (SI Brochure, 9th edition) — https://www.bipm.org/en/publications/si-brochure (standard, retrieved 2026-09-24)
- Wikipedia – Conversion of units — https://en.wikipedia.org/wiki/Conversion_of_units (reference, retrieved 2026-09-24)