centimetres to inches converter
1 cm = 0.3937007874 in. Type a value in either box — the other side updates instantly, using the exact definition factor, not a rounded shortcut. The everyday bridge between metric product specs and US listings — phone screens, monitor diagonals and furniture dimensions all cross this pair.
Rate: 1 cm = 0.3937007874 in · 1 in = 2.54 cm · As a tape-measure fraction:
Inches as fractions
Tape measures and rulers are marked in sixteenths of an inch, not decimals. For the worked example on this page, 11.811 in is closest to 11 13/16 in — the fraction is an approximation, off by 1.48e-3 in (about 0.0375 mm). The fraction readout in the converter above updates with whatever you type, so you can read any result straight onto a ruler.
Formula and a worked example
inches = centimetres × 0.3937007874. Worked example: 30 cm × 0.3937007874 = 11.811024 in. To go back, divide by the same factor (or multiply by 2.54).
Where the factor comes from: The inch is defined as exactly 2.54 centimetres (25.4 mm) under the 1959 international yard and pound agreement. Factors on UnitPairs follow the NIST definitions, so results agree between pages to the last digit shown.
centimetres to inches chart
| centimetres (cm) | inches (in) |
|---|---|
| 1 | 0.393701 |
| 2 | 0.787402 |
| 5 | 1.968504 |
| 10 | 3.937008 |
| 15 | 5.905512 |
| 20 | 7.874016 |
| 25 | 9.84252 |
| 30 | 11.811024 |
| 40 | 15.748031 |
| 50 | 19.685039 |
| 75 | 29.527559 |
| 100 | 39.370079 |
| 150 | 59.055118 |
| 170 | 66.929134 |
| 180 | 70.866142 |
| 200 | 78.740157 |
Questions
How many inches are in one centimetre?
Exactly 0.3937007874 in — that is the rate this converter applies in both directions.
How do I convert cm to in by hand?
Multiply the centimetres value by 0.3937007874. For a rough mental estimate, 0.394 is usually close enough — but use the full factor for anything you plan to build, buy or dose.
How accurate is this converter?
The factors are the exact international definitions, so the only rounding is in the display — results are shown to six decimal places, and the underlying value is never pre-rounded.
Related conversions
- inches to centimetres — the reverse of this page
- inches to centimetres
- metres to feet
- feet to metres
- kilometres to miles
- miles to kilometres
- centimetres to feet
- Height converter — centimetres to feet and inches
- Full conversion chart — every pair on one page