One inch equals exactly 2.54 centimetres. To convert inches to cm, multiply by 2.54. To convert cm to inches, divide by 2.54. This is an exact, defined conversion (not an approximation) established in 1959 by the International Yard and Pound Agreement. 12 inches = 30.48 cm (one foot); 36 inches = 91.44 cm (one yard).
Inches are used in the US, Canada (for personal heights), and some UK contexts. Centimetres are standard in science, medicine, and most global commerce. Screen and monitor sizes are quoted in inches (a 27-inch monitor diagonal), while European consumer electronics list dimensions in centimetres. Dress patterns and clothing measurements often require conversion between systems when using international patterns or shopping across markets.
Inches to Centimetres
Inches
cm
Common Reference
1
2.54
Width of a thumb
6
15.24
School ruler (half)
12
30.48
One foot
18
45.72
Typical laptop screen
24
60.96
Two feet
36
91.44
One yard
Inches to Centimeters: The Universal Clothing and Screen Conversion
One inch equals exactly 2.54 cm. Multiplying inches by 2.54 gives centimeters. Screen sizes (TVs, monitors, phones) are marketed in diagonal inches in the US but centimeters in many European and Asian markets. A 65-inch television diagonal equals 165.1 cm. Waist measurements for men’s trousers in the US are in inches (32, 34, 36); European sizing uses centimeters. International athletic equipment standards (gym mats, gymnastics apparatus, ring sizes, court markings) use centimeters. Rain gauge and snowfall measurements are in inches in the US; worldwide meteorological data uses millimeters. Pipe thread gauges nominally use inches but are specified in fractions; converting to metric millimeter equivalents aids global sourcing. The 2.54 factor is exact by international agreement, making inch-centimeter conversion losslessly precise to any desired decimal place.
