Inches to centimetres
Enter a measurement in inches to get centimetres. This is the conversion for customs forms, international carrier tools, and anywhere a metric dimension is expected.
Type a measurement in inches and the conversion appears here.
When shipping needs metric
Customs declarations, international carrier portals, and most of the world's rate tables work in centimetres. A US seller measuring a box with an imperial tape needs the metric figure for the paperwork, and the two must describe the same box or the declaration is wrong.
The conversion
One inch is defined as exactly 2.54 centimetres. It is a definition rather than a measurement, so the conversion is exact: multiply inches by 2.54.
- 1 in = 2.54 cm
- 12 in = 30.48 cm
- 108 in = 274.32 cm, a common carrier length cap
Quick reference
| Inches | Centimetres |
|---|---|
| 1 in | 2.54 cm |
| 2 in | 5.08 cm |
| 6 in | 15.24 cm |
| 9 in | 22.86 cm |
| 12 in | 30.48 cm |
| 14 in | 35.56 cm |
| 18 in | 45.72 cm |
| 24 in | 60.96 cm |
| 36 in | 91.44 cm |
| 108 in | 274.32 cm |
Edge cases worth knowing
- Round the metric figure up, not down. A box declared slightly smaller than it is can be re-measured and re-rated at the carrier's expense, not yours.
- Convert each dimension, not the volume. Converting cubic inches to cubic centimetres means multiplying by 2.54 three times, which is 16.387 — not 2.54.
- Fractional inches trip people up. A tape reading of 9¾ in is 9.75 in, not 9.34.
Common questions
- How many centimetres are in an inch?
- Exactly 2.54. This has been the definition of the inch since 1959.
- How do I convert a whole box?
- Convert each of the three measurements separately. A 12 × 9 × 6 in box is 30.48 × 22.86 × 15.24 cm.
- What about cubic inches to cubic centimetres?
- Multiply by 16.387, which is 2.54 cubed. The box volume calculator does this for you.
- Do carriers accept measurements in either unit?
- Most international portals accept both, but the form usually fixes one. Enter the unit the form asks for rather than converting in your head.