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Convert inches to centimeters
Type a number and see it converted as you type. 1 inch = 2.54 centimeters, so the conversion is simply × 2.54.
The formula
centimeters = inches × 2.54
inches to centimeters — quick reference
| inches (in) | centimeters (cm) |
|---|---|
| 1 | 2.54 |
| 2 | 5.08 |
| 3 | 7.62 |
| 4 | 10.16 |
| 5 | 12.7 |
| 10 | 25.4 |
| 15 | 38.1 |
| 20 | 50.8 |
| 25 | 63.5 |
| 50 | 127 |
| 75 | 190.5 |
| 100 | 254 |
| 250 | 635 |
| 500 | 1,270 |
| 1,000 | 2,540 |
Quarter it, multiply by ten, then add a little back
The four-inches-to-ten-centimetres anchor runs in this direction too: divide the inches by four and multiply by ten. 36 inches gives 90 cm against a true 91.44, and 12 inches gives 30 against 30.48. The result is always about one and a half per cent light, so adding that back is close enough for anything but joinery.
Heights need the feet folded in first. Convert to inches - five foot ten is 70 - then apply the same method for 175 cm, and correct upward to reach the true 177.8. Working feet and inches separately, at 30 cm and 2.5 cm, compounds two roundings in the same direction and drifts further.
An exact conversion still goes wrong when you round too early
The inch is defined as exactly 25.4 mm rather than measured, a legacy of the 1959 international yard and pound agreement, so there is no uncertainty in the conversion itself. Every error comes from rounding: treating an inch as 2.5 cm loses 1.6 per cent, which over a 96-inch run of worktop is a missing 3.8 cm.
Some imperial numbers are not lengths to be converted at all. A 205/55 R16 tyre mixes millimetres, a percentage and a 16-inch rim in one code. Shoe sizes are their own scales, and Mondopoint is already stated in millimetres of foot length, so converting a UK size to centimetres produces a number that means nothing.
Questions
How many centimeters are in 1 inch?
1 inch = 2.54 centimeters. To convert any amount, multiply by 2.54.
What is the formula to convert inches to centimeters?
centimeters = inches × 2.54. That is exactly what the calculator above does, so you can check its working.
Is the conversion exact?
Yes, by definition: since 1959 an inch is exactly 25.4 mm, which fixes every imperial-to-metric length conversion exactly. The decimals you see are only rounded for display.
Updated 2026-07-20. The conversion runs in your browser — nothing is uploaded.