How to convert cm to inches
Divide the centimeters by 2.54. An inch is defined as exactly 2.54 centimeters, so there's no rounding in the rule itself. To go from inches to centimeters, multiply by 2.54.
Here it is with your numbers:
- Divide by 2.54: 30 ÷ 2.54 = 11.81102362….
- Round to 4 decimals: 11.811 in.
It means something 30 centimeters long measures 11.811 inches on a US tape measure.
Source NIST Handbook 44 (2026) · Appendix C, General Tables of Units of Measurement ↗
Centimeters to inches chart
| Centimeters | Inches |
|---|---|
| 1 cm | 0.3937 in |
| 2 cm | 0.7874 in |
| 3 cm | 1.1811 in |
| 4 cm | 1.5748 in |
| 5 cm | 1.9685 in |
| 6 cm | 2.3622 in |
| 7 cm | 2.7559 in |
| 8 cm | 3.1496 in |
| 9 cm | 3.5433 in |
| 10 cm | 3.9370 in |
| 12 cm | 4.7244 in |
| 15 cm | 5.9055 in |
| 20 cm | 7.8740 in |
| 25 cm | 9.8425 in |
| 30 cm | 11.8110 in |
| 40 cm | 15.7480 in |
| 50 cm | 19.6850 in |
| 60 cm | 23.6220 in |
| 70 cm | 27.5591 in |
| 75 cm | 29.5276 in |
| 80 cm | 31.4961 in |
| 90 cm | 35.4331 in |
| 100 cm | 39.3701 in |
| 150 cm | 59.0551 in |
| 160 cm | 62.9921 in |
| 170 cm | 66.9291 in |
| 180 cm | 70.8661 in |
| 190 cm | 74.8031 in |
| 200 cm | 78.7402 in |
Inches to centimeters chart
| Inches | Centimeters |
|---|---|
| 1 in | 2.5400 cm |
| 2 in | 5.0800 cm |
| 3 in | 7.6200 cm |
| 4 in | 10.1600 cm |
| 5 in | 12.7000 cm |
| 6 in | 15.2400 cm |
| 7 in | 17.7800 cm |
| 8 in | 20.3200 cm |
| 9 in | 22.8600 cm |
| 10 in | 25.4000 cm |
| 11 in | 27.9400 cm |
| 12 in | 30.4800 cm |
| 18 in | 45.7200 cm |
| 24 in | 60.9600 cm |
| 36 in | 91.4400 cm |
| 48 in | 121.9200 cm |
| 60 in | 152.4000 cm |
| 72 in | 182.8800 cm |
Every converted figure is rounded to 4 decimals. Inches to centimeters always comes out exact, because 2.54 has only two decimals.
Is an inch exactly 2.54 cm?
Yes. In the US, 1 inch is defined as exactly 2.54 centimeters, and a foot is 12 inches, so a foot is exactly 30.48 cm. NIST, the US agency in charge of weights and measures, lists both as exact in Handbook 44. Going the other way, 1 cm is 0.393700787… inches, a decimal that never ends, which is why the answer is rounded.
Source NIST Guide to the SI (SP 811) · Appendix B.8, factors for units listed alphabetically ↗
FAQs
Is 2.5 cm the same as 1 inch?
Close, but not quite. 1 inch is exactly 2.54 cm, so 2.5 cm is 0.9843 in. Over 100 inches the difference adds up to 4 cm.
Source NIST Handbook 44 (2026) · Appendix C, General Tables of Units of Measurement ↗
Is 1 cm equal to 1 inch?
No. 1 cm is 0.3937 inches, less than half an inch. It takes 2.54 cm to make 1 inch.
What size is 60 cm in inches?
60 cm is 23.622 inches: 60 ÷ 2.54 = 23.622, which is 1 ft 11.622 in.
What size is 20 cm in inches?
20 cm is 7.874 inches: 20 ÷ 2.54 = 7.874, a bit under 8 inches.
What does 10 cm look like in inches?
10 cm is 3.937 inches, just under 4 inches: 10 ÷ 2.54 = 3.937.
Sources
- NIST Handbook 44 (2026): Appendix C, General Tables of Units of Measurement
- NIST Guide to the SI (SP 811): Appendix B.8, factors for units listed alphabetically