CM to Inches Converter
Convert centimeters to inches instantly. Also converts inches back to cm — plus a full reference table and height converter.
How to Convert CM to Inches
To convert centimetres to inches, multiply the value by 0.393701. This is because 1 inch is defined as exactly 2.54 centimetres, so dividing by 2.54 (or equivalently multiplying by 1/2.54 = 0.393701) gives the inch value. For example: 30 cm × 0.393701 = 11.811 inches. For quick mental maths, a rough approximation is to divide by 2.5 — not exact but useful for estimates.
Common CM to Inches Conversions
Some frequently needed conversions: 1 cm = 0.394 in | 5 cm = 1.969 in | 10 cm = 3.937 in | 15 cm = 5.906 in | 20 cm = 7.874 in | 25 cm = 9.843 in | 30 cm = 11.811 in | 50 cm = 19.685 in | 100 cm = 39.370 in | 150 cm = 59.055 in | 180 cm = 70.866 in (5 ft 10.9 in)
CM to Inches for Height Conversion
Height is commonly expressed in feet and inches in the US, UK, and India for personal measurements, while centimetres are used in medical, scientific, and most international contexts. To convert height from cm to feet and inches: first divide by 30.48 to get the total feet (decimal). The integer part is the feet. Multiply the decimal part by 12 to get the remaining inches. Example: 170 cm ÷ 30.48 = 5.577 feet → 5 feet + (0.577 × 12) = 5 feet 6.9 inches.
Why 1 Inch = 2.54 cm Exactly?
Since 1959, the international yard and pound agreement defined the inch as exactly 2.54 centimetres. This makes it an exact defined relationship, not a measurement approximation. All conversions between inches and centimetres derive from this single exact definition.