Cm to Inches: Centimeters to Inches Converter
Decimal inches and the nearest tape-measure fraction together, because a decimal isn't much use with a ruler in your hand.
Enter a number.
Converting a person's height? The height converter gives feet and inches in the format people say out loud, and answers the boundary questions like whether 170 cm is 5 foot 6 or 5 foot 7.
The formula
cm = in × 2.54 (exact)
2.54 is exact by definition rather than a measured approximation, so both directions are exact. That is unusual: most conversion pairs have one exact direction and one rounded one, as explained on the exact versus rounded page.
Conversion table
| Centimeters | Inches (decimal) | Nearest 1/16 in | Feet and inches |
|---|---|---|---|
| 10 cm | 3.937 | 3 15/16 | 0 ft 3.9 in |
| 15 cm | 5.906 | 5 7/8 | 0 ft 5.9 in |
| 20 cm | 7.874 | 7 7/8 | 0 ft 7.9 in |
| 25 cm | 9.843 | 9 13/16 | 0 ft 9.8 in |
| 30 cm | 11.811 | 11 13/16 | 0 ft 11.8 in |
| 40 cm | 15.748 | 15 3/4 | 1 ft 3.7 in |
| 50 cm | 19.685 | 19 11/16 | 1 ft 7.7 in |
| 60 cm | 23.622 | 23 5/8 | 1 ft 11.6 in |
| 100 cm | 39.370 | 39 3/8 | 3 ft 3.4 in |
| 150 cm | 59.055 | 59 1/16 | 4 ft 11.1 in |
| 180 cm | 70.866 | 70 7/8 | 5 ft 10.9 in |
| 200 cm | 78.740 | 78 3/4 | 6 ft 6.7 in |
Reading the fraction column
Imperial tapes are divided into halves, quarters, eighths and sixteenths, all fractions with a power of two on the bottom. Most centimeter values don't land on one of those marks, so the fraction column shows the nearest sixteenth rather than pretending there is an exact match.
For finer work, the decimal to fraction converter goes down to sixty-fourths and reports how far the rounded value sits from the true one.
Common questions
How many inches is 10 cm?
10 centimeters is 3.937 inches, which is just under 3 15/16 on a tape measure.
Is 1 inch exactly 2.54 cm?
Yes. The inch has been defined as exactly 2.54 centimeters since the 1959 international yard and pound agreement. It is a definition, not a measurement, so it is exact at any precision.
What is 30 cm in inches?
30 centimeters is 11.811 inches, a little under a foot. A 30 cm ruler is slightly shorter than a 12 inch one.
How do I convert cm to inches in my head?
Divide by 2.5 and subtract a little. Dividing by 2.5 overestimates by about 1.6 percent, which is close enough for rough work and easy to do mentally.
Related converters and guides
Sources
- NIST Guide to the SI, Appendix B: Conversion Factors. National Institute of Standards and Technology. Source for every conversion factor on this page, and for which factors are exact rather than rounded.