Convert Inch to Centimeter
Conversion Formula
cm = in × 2.54To convert Inch to Centimeter, use the formula above. This is the standard conversion factor used worldwide.
Conversion Table
| Inch (in) | Centimeter (cm) |
|---|---|
| 1 | 2.5400 |
| 12 | 30.4800 |
| 24 | 60.9600 |
| 100 | 254.0000 |
Why convert Inch to Centimeter
A US carpenter sizing lumber, a hobbyist designing a 3D-printed part, or a seller filling out an international customs form needs the metric figure because the buyer or supplier on the other end only accepts centimeters. It runs opposite to the height lookups that dominate the centimeter to inch page: the starting number is already in a unit most of the world doesn't use day to day.
Where the number comes from
Because the inch is fixed at exactly 2.54 centimeters, converting the other way is just as exact: multiply your inch figure by 2.54 and the result is not an approximation. This is one of the few imperial to metric conversions you can trust to as many decimal places as you need, which matters in manufacturing where a rounded conversion can push a part out of spec.
Quick reference
| 1 in | 2.54 cm | exact |
| 1 ft (12 in) | 30.48 cm | |
| 0.5 in | 1.27 cm | a common bolt or pipe diameter |
| 8.5 in | 21.59 cm | US letter paper width |
| 12 in | 30.48 cm | |
| 36 in | 91.44 cm | one yard |
Common mistakes
- Engineering drawings sometimes carry inch measurements to two decimal places, like 3.25 in, and get converted with a spreadsheet formula that truncates the output, silently dropping precision the original drawing had.
- Fractional inches, quarter, eighth, sixteenth, need converting to decimal first, 5/8 in becomes 0.625 in, before multiplying by 2.54, and skipping that step is a common source of wrong metric dimensions.
Frequently Asked Questions
How do I convert a fractional inch measurement like 3/8 in?
Convert the fraction to a decimal first, 3 divided by 8 equals 0.375, then multiply by 2.54 to get 0.9525 cm.
Why do manufacturing drawings need exact conversions rather than rounded ones?
Tolerances stack across a part. A rounded conversion applied to several dimensions on the same drawing can push the finished piece outside its acceptable tolerance band, especially where it needs to mate with a metric-standard component.
Is millimeters or centimeters more common on international spec sheets?
Millimeters are the standard unit on most engineering drawings outside the US. Multiply your centimeter result by 10 to get millimeters, or skip the centimeter step and multiply inches by 25.4 directly.
Does US letter paper (8.5 x 11 in) match A4?
No. A4 measures 21.0 by 29.7 cm, a genuinely different shape from converted US letter (21.59 by 27.94 cm), which is why US documents do not print cleanly on A4 without rescaling.