Unit Converters
Inches to cm converter.
Type inches or centimetres and the other box updates as you type. One inch is exactly 2.54 cm, so cm = inches × 2.54. Runs in your browser; nothing is sent anywhere.
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Result
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Answer
12 in is 30.48 cm. 1 in = 2.54 cm exactly.
Formula
cm = inches × 2.54
Take 12 in. cm = inches × 2.54 gives 30.48 cm. Going back: 30.48 cm converts back to 12 in.
Quick estimate: multiply inches by 2.5, then add a little (about 2% more).
Inches to cm table (1 to 100)
| Inches (in) | Centimetres (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 |
| 60 | 152.4 |
| 70 | 177.8 |
| 75 | 190.5 |
| 80 | 203.2 |
| 90 | 228.6 |
| 100 | 254 |
Examples
- 1 in = 2.54 cm
- 6 in = 15.24 cm
- 12 in = 30.48 cm
- 36 in = 91.44 cm
Source
Conversion factors and formulas: NIST SP 811, Appendix B.8: inch to centimeter, 2.54 E+00; NIST Handbook 44 (2026), Appendix C: 1 inch = 2.54 cm. Retrieved 2026-10. Results are rounded for display to 4 decimal places; the arithmetic itself is not rounded.
FAQ
How many centimetres are in 1 inch?
1 in is 2.54 cm. 1 in = 2.54 cm exactly.
What is the formula to convert inches to centimetres?
cm = inches × 2.54. For 6 in that gives 15.24 cm.
Is the conversion factor exact?
Yes for the stated definition. 1 in = 2.54 cm exactly. The tool shows results rounded to four decimal places; the underlying arithmetic is not rounded.
How do I estimate it in my head?
Quick estimate: multiply inches by 2.5, then add a little (about 2% more). Use the exact factor when accuracy matters.
What is 12 in in centimetres?
12 in is 30.48 cm.
Disclaimer
Informational arithmetic using the published factors above. For legal-for-trade, engineering or medical use, check against the governing standard.