The factor
cm = inches × 2.54, with no rounding, because 2.54 cm is the definition of an inch. So 7 inches is 17.78 cm exactly, not about 17.78.
Worked examples
Common inch measures in centimetres:
| Inches | Centimetres |
|---|---|
| 1 in | 2.54 cm |
| 6 in | 15.24 cm |
| 12 in | 30.48 cm |
| 24 in | 60.96 cm |
| 32 in | 81.28 cm |
| 55 in | 139.7 cm |
| 65 in | 165.1 cm |
A 55-inch television is 139.7 cm across the diagonal, not across the width: screen sizes are measured corner to corner.
Questions
How many cm is 5 feet 6 inches?
5 feet is 60 inches; add 6 and it is 66 inches, which is 167.64 cm. Type 66 here.
What about fractions of an inch?
Type them as decimals: ½ is 0.5, ¼ is 0.25, ⅛ is 0.125 and 1/16 is 0.0625. So 3⅜ inches is 3.375, which is 8.5725 cm.