Convert centimetres to inches
Convert cm to inches with exact 2.54 arithmetic, tape-measure fractions down to 1/16, a feet-and-inches readout and column batch mode.
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- Free, no account
Decimals are fine. You can also paste “30 cm” or a whole column of values in Batch mode.
inches = centimetres ÷ 2.54 = 30 ÷ 2.54 = 11.8110 in 1 cm = 0.393701 in
| centimetres | inches | Nearest 1/16 in |
|---|---|---|
| 1 cm | 0.3937 in | 3/8 in |
| 2 cm | 0.7874 in | 13/16 in |
| 3 cm | 1.1811 in | 1 3/16 in |
| 5 cm | 1.9685 in | 1 15/16 in |
| 10 cm | 3.9370 in | 3 15/16 in |
| 15 cm | 5.9055 in | 5 7/8 in |
| 20 cm | 7.8740 in | 7 7/8 in |
| 25 cm | 9.8425 in | 9 13/16 in |
| 30 cm | 11.8110 in | 11 13/16 in |
| 40 cm | 15.7480 in | 15 3/4 in |
| 50 cm | 19.6850 in | 19 11/16 in |
| 60 cm | 23.6220 in | 23 5/8 in |
| 75 cm | 29.5276 in | 29 1/2 in |
| 90 cm | 35.4331 in | 35 7/16 in |
| 100 cm | 39.3701 in | 39 3/8 in |
| 120 cm | 47.2441 in | 47 1/4 in |
| 150 cm | 59.0551 in | 59 1/16 in |
| 180 cm | 70.8661 in | 70 7/8 in |
| 200 cm | 78.7402 in | 78 3/4 in |
Centimetres to inches, exactly
The inch has been a metric unit since 1959. That year the United States, the United Kingdom, Canada, Australia, New Zealand and South Africa signed the international yard and pound agreement, which fixed the inch at exactly 2.54 centimetres. It is not a measured ratio that gets refined with better instruments; it is a definition, so every conversion on this page is exact to as many decimal places as you ask for.
That gives you two ways to do the arithmetic, and they are the same arithmetic:
- Divide by 2.54. 30 cm ÷ 2.54 = 11.811 in.
- Multiply by 0.3937007874. 30 × 0.3937007874 = 11.811 in.
Dividing is safer by hand because 2.54 is short and memorable while the reciprocal is a recurring decimal you will inevitably truncate. This page divides, using arbitrary-precision decimal arithmetic rather than the browser's binary floating point, so you never see the familiar 11.810999999999998 artefact.
Why the fraction column matters
No imperial tape measure has decimal inches printed on it. It has sixteenths. A result of 11.811 in is useless at the bench until you know it is a hair under 11 and thirteen-sixteenths, which is what the fraction readout gives you. The three common resolutions are:
| Resolution | Step size | Used for |
|---|---|---|
| 1/16 in | 1.5875 mm | Builder's tape, general carpentry, fabric |
| 1/32 in | 0.7938 mm | Cabinetmaking, sheet goods |
| 1/64 in | 0.3969 mm | Machining, engraving, model making |
The converter snaps to sixteenths by default because that is what most people are holding. The millimetres-to-inches page offers all three side by side if you need finer work.
Common centimetre measurements in inches
A few conversions come up constantly and are worth knowing by heart. A 30 cm ruler is 11.81 in, just under a foot. A4 paper is 21 × 29.7 cm, which is 8.27 × 11.69 in — noticeably narrower and taller than US Letter at 8.5 × 11 in, which is why PDFs made for one paper size print with odd margins on the other. Airline cabin bag limits of 55 × 40 × 20 cm are 21.7 × 15.7 × 7.9 in.
Heights and the feet-and-inches readout
For a human height, the number you actually want is not decimal inches. 175 cm is 68.9 in, which nobody says out loud; it is 5 ft 8.9 in, and colloquially "five foot nine". The feet-and-inches readout does that split for you, carrying the remainder correctly so you never get the nonsense "5 ft 12 in" that naive rounding produces.
Converting a whole column
The Batch tab takes a pasted spreadsheet column and returns a matching one. Blank lines are preserved so the output pastes back in register, and any line that is not a number is left blank rather than quietly guessed at — a silent wrong number in a parts list is far worse than a visible gap. Nothing you paste is transmitted; the conversion runs in this tab.
Questions
How many inches is 1 cm?
One centimetre is 0.3937007874 inches, because an inch is defined as exactly 2.54 cm. Ten centimetres is 3.937 in, and 100 cm is 39.37 in.
Why does the answer show a fraction as well as a decimal?
Because no tape measure has decimal inches on it. The fraction column snaps the answer to the nearest sixteenth, which is the smallest mark on a standard imperial tape, so you can cut to it directly.
Is 2.54 an approximation?
No. Since the 1959 international yard and pound agreement, the inch is defined as exactly 25.4 mm. Every conversion on this page is exact to the number of decimals you ask for — the arithmetic runs in arbitrary-precision decimal, not binary floating point.
Can I convert a whole spreadsheet column?
Yes. Switch to the Batch tab and paste the column. Blank lines are preserved so the result pastes back into the spreadsheet in register, and anything unreadable is left blank rather than silently guessed at.
Does anything I type get uploaded?
No. The page contains the conversion table and the arithmetic; there is no server to send anything to. You can turn off Wi-Fi and it still works.