Centimetres to inches
Convert centimetres to inches. Divide by 2.54 for an exact result, with a reference table of common heights and paper sizes.
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The formula
inches = centimetres ÷ 2.54The factor is exact, not approximate. Since the international yard and pound agreement of 1959, one inch is defined as exactly 2.54 centimetres, so this conversion loses no precision in either direction.
To go the other way, multiply by 2.54. See inches to cm.
Quick reference
| Centimetres | Inches | Roughly |
|---|---|---|
| 1 cm | 0.3937 in | width of a fingernail |
| 2.54 cm | 1 in | exactly one inch |
| 10 cm | 3.937 in | |
| 15.24 cm | 6 in | |
| 30.48 cm | 12 in | one foot |
| 100 cm | 39.37 in | one metre |
Common heights
Heights are usually quoted in feet and inches rather than inches alone, so both are given:
| Centimetres | Inches | Feet and inches |
|---|---|---|
| 150 cm | 59.1 in | 4′ 11″ |
| 160 cm | 63.0 in | 5′ 3″ |
| 170 cm | 66.9 in | 5′ 7″ |
| 175 cm | 68.9 in | 5′ 9″ |
| 180 cm | 70.9 in | 5′ 11″ |
| 190 cm | 74.8 in | 6′ 3″ |
To convert inches into feet and inches, divide by 12. The whole number is the feet, the remainder the inches.
Paper sizes
A-series paper is defined in millimetres, so its inch equivalents are never round numbers:
| Size | Centimetres | Inches |
|---|---|---|
| A4 | 21.0 × 29.7 cm | 8.27 × 11.69 in |
| A5 | 14.8 × 21.0 cm | 5.83 × 8.27 in |
| A3 | 29.7 × 42.0 cm | 11.69 × 16.54 in |
US Letter, by contrast, is defined in inches as 8.5 × 11 in, which is 21.59 × 27.94 cm. This is why documents laid out for one standard never quite fit the other.
Estimating in your head
An inch is a little under two and a half centimetres. To go from centimetres to inches quickly, divide by 2.5 and the answer will be about 1.6% low, near enough for a tape measure, though not for anything machined.