Inch (in) to Centimeter (cm)
Convert inches to centimeters. One inch is exactly 2.54 centimeters — 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 centimeters. 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 centimeters. 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 US retained the customary system after independence. Congress authorized the metric system in 1866 but never mandated it, so inches remain the everyday standard for screen sizes, clothing waist measurements, and construction lumber.