1 Inch to Centimetres
1 inch is exactly 2.54 cm.
1 inch = 2.54 cm
Type in either box. Inches also take fractions and feet: 1 1/2, 3/4, 5'7", 5 ft 7 in.
How to convert 1 inch to cm
Multiply by 2.54, the exact number of centimetres in an inch:
1 in × 2.54 = 2.54 cm
No rounding is involved — the inch is defined as 2.54 cm, so 2.54 cm is the exact answer, not an approximation. In millimetres that is 25.4 mm, and in metres 0.0254 m.
The inch is the base unit here: since 1959 it has been defined as exactly 2.54 cm, so this figure is not a rounded approximation but the definition itself. For a sense of scale, a US quarter is 0.955 in (24.26 mm) across — an inch is a shade wider.
1 inch in other units
| Centimetres | 2.54 cm |
| Millimetres | 25.4 mm |
| Metres | 0.0254 m |
Inches to cm near 1
Need a different value? Type it into the converter above, or go back to the full cm to inches converter.
Frequently asked questions
How many centimetres is 1 inch?
1 inch is exactly 2.54 centimetres. One inch is defined as 2.54 cm, so multiply 1 by 2.54.
How do I estimate 1 inch in cm without a calculator?
Multiply by 2.5, then add a little: 1 × 2.5 = 2.5, and the exact answer of 2.54 cm is 1.6% higher. For most everyday purposes, 2.5 is close enough.