How Many Cm in an Inch? Exact Conversion Explained
How many cm in an inch? There are exactly 2.54 centimetres in one inch. This is the internationally agreed conversion, so it never changes and works for every measurement, from screen sizes and paper to fabric, height and DIY projects.
The Short Answer: 1 Inch Equals 2.54 Cm
To convert inches to centimetres, multiply the number of inches by 2.54. For example, 5 inches is 12.7 cm, 10 inches is 25.4 cm, and 12 inches is 30.48 cm. To go the other way, divide centimetres by 2.54 to get inches.
Why 2.54 Is the Exact Figure
The inch was defined in terms of the metric system in 1959, when an international agreement fixed it at exactly 25.4 millimetres. That makes the conversion precise rather than approximate, which matters in engineering, printing, sewing and anywhere a small error can add up over a long measurement.
Common Inch to Cm Conversions
Some conversions come up again and again: 1 inch is 2.54 cm, 2 inches is 5.08 cm, 6 inches is 15.24 cm, and 24 inches is 60.96 cm. Remembering that 10 inches is 25.4 cm gives you a useful mental anchor, and you can add or subtract from there for nearby values.
Convert Lengths Instantly
For longer lists, decimals or other units such as feet, yards, metres and millimetres, use our free Length Converter. Enter any value, choose your units and get an accurate result in seconds, without doing the maths by hand.