Frequently Asked Questions

There are exactly 2.54 centimetres in one inch or 25.4 millimetres. To convert inches to cm, multiply your number of inches by 2.54. For example, 10 inches is 25.4 cm.

Divide the centimetres by 2.54. For example, 50 ÷ 2.54 = 19.69 inches. Our tool does this automatically when you press the swap button, and it also shows the answer in feet and inches.

It's exact. Since 1959 the inch has been defined as precisely 2.54 cm by international agreement, so there's no approximation involved. If you see a rounded number, that's just because of decimal places — the 2.54 itself doesn't change..

5 ft 9 in is 175.26 cm. Work it out by turning the feet into inches first: 5 × 12 = 60, plus 9 gives 69 inches. Then 69 × 2.54 = 175.26 cm.

A 32 inch waist is 81.28 cm, usually written as 81 cm or 82 cm on European labels. Measure round your natural waistline with the tape flat, not pulled tight, for the closest match.

The screen measures 139.7 cm diagonally, because 55 × 2.54 = 139.7. The cabinet itself is usually near 123 cm wide and about 71 cm tall, so measure your actual space rather than the screen size.

An eighth of an inch is 0.125 inches, so 0.125 × 2.54 = 0.3175 cm, or 3.18 mm. For other tape measure marks, use the fractions chart higher up this page.

Britain began going metric in the 1960s but never finished the job. Older generations learned imperial road signs stayed in Miles, trades kept inches for pipe and timber sizes. So both systems sit side by side and people convert between them constantly.

For a rough guess, yes. For anything you're cutting, no. 2.5 instead of 2.54 loses about 1.6%, which is 4 cm over 100 inches.