Inch (in) to Centimetre (cm)
Convert inches to centimetres. One inch is exactly 2.54 centimetres — a definition agreed internationally in 1959. Useful when buying electronics with inch-based screen sizes, reading American clothing measurements, or working with technical specifications from overseas.
Frequently asked questions
1 inch is exactly 2.54 centimetres. This is an internationally agreed definition, not an approximation — established in 1959 by a formal agreement between English-speaking nations.
A 55-inch television has a screen diagonal of 55 × 2.54 = 139.7 centimetres. Screen sizes are always measured diagonally, corner to corner.
Multiply the number of inches by 2.54. Example: 12 inches × 2.54 = 30.48 cm. Quick mental check: 10 inches is 25.4 cm; double and add a fifth for a rough estimate.
The inch is legally retained in the UK for road signs (alongside miles) and is widely used informally for screen sizes, waist measurements and DIY timber. The UK officially adopted the metric system in 1965 but has kept the inch in everyday use for several categories.