Centimeters to Inches Converter

The cm to inches formula

One inch is defined as exactly 2.54 centimetres. To go from centimetres to inches, divide by 2.54; to go from inches to centimetres, multiply by 2.54. No other constant is involved, and because 2.54 is exact, so is every result before display rounding.

inches = cm ÷ 2.54  ·  cm = inches × 2.54
feet = whole part of (inches ÷ 12), remaining inches = inches − 12 × feet

Worked examples

Example 1: a height of 170 cm

170 ÷ 2.54 = 66.9291 in. Twelve goes into 66.93 five times (60 in), leaving 6.93 in, so the height is 5 ft 6.9 in, usually said as "five foot seven".

Example 2: a 32-inch waist

32 × 2.54 = 81.28 cm. Clothing labels in metric sizing often round this to 81 cm.

Example 3: a 15.6-inch laptop screen

15.6 × 2.54 = 39.624 cm measured diagonally — the screen size is the diagonal, not the width.

Example 4: an A4 sheet

A4 paper is 21.0 × 29.7 cm. Dividing each by 2.54 gives 8.27 × 11.69 in, slightly narrower and longer than US Letter at 8.5 × 11 in.

Centimetres to inches table

Inches to centimetres table

Heights in feet and inches

Estimating in your head

For a rough figure, multiply centimetres by 0.4: 50 cm × 0.4 = 20 in (the exact answer is 19.69 in). Going the other way, multiply inches by 2.5: 12 in × 2.5 = 30 cm (exact: 30.48 cm). Both shortcuts are within about 2%, good enough for a shop shelf but not for a carpentry cut. A ruler that shows both scales is still the fastest check: 10 cm is just under 4 in, and 1 ft is just over 30 cm.

Common uses

The cm-to-inch conversion appears daily in clothing and shoe sizing, body measurements for fitness tracking, height on forms and dating profiles, screen and TV sizes, picture frames and paper sizes, bicycle frames and wheel diameters, and DIY projects using hardware from different countries. Doctors in the US often record infant length in inches while growth charts from the World Health Organization use centimetres, so parents frequently convert between them. For metres, feet, yards and miles too, use the full length converter.

Precision and rounding

Results are shown to four decimal places. Round to suit the measurement: a tailor's tape is read to the nearest half centimetre or eighth of an inch, so 81.28 cm is best stated as 81.5 cm or 32 in. Fractional inches used in US hardware are powers of two — halves, quarters, eighths, sixteenths — so 0.3125 in is 5/16 in. To turn a decimal inch into a fraction, multiply by 16 and round, then simplify with the fraction calculator.

Reading a ruler with both scales

Most rulers and tape measures sold internationally carry centimetres on one edge and inches on the other. The metric edge is divided into millimetres, ten to a centimetre, so a reading such as 12.7 cm is read directly. The inch edge is divided into halves, quarters, eighths and sixteenths, so the same length appears as exactly 5 in. Lining a mark up on one edge and reading across to the other is a quick physical check of a conversion. When marking a cut, measure in the same system as the plans to avoid compounding small rounding differences.