When you need this conversion
Online shopping across countries is the classic case: a European sofa listed as 200 cm wide, a phone case for a 15 cm device, clothing measurements in centimeters when you think in inches. Screen sizes, picture frames and luggage limits come up often too.
Quick reference
- 1 cm = 0.3937 in
- 2.5 cm ≈ 0.98 in (about an inch)
- 10 cm = 3.937 in
- 30 cm = 11.811 in
- 100 cm = 39.3701 in (about 3 ft 3.37 in)
Estimating in your head
Divide by 2.5 and add a little. 40 cm ÷ 2.5 = 16, and the real answer is 15.75 in. For quick shopping comparisons that’s close enough; for anything that must fit, use the exact value.
Common mistakes
Dividing by 2.5 for things that must fit. On 200 cm, the shortcut gives 80 in, but the real figure is 78.74 in. That 1.26-inch gap matters for furniture and doorways.
Confusing cm with mm. Many product specs are in mm. 150 mm is 15 cm, which is 5.906 in.
For heights, use cm to feet and inches. For the reverse, use inches to cm.