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Centimeter (cm)

Also called: cm, centimetre, centimeters

Definition: The centimeter is a metric unit of length equal to one hundredth of a meter (0.01 m); exactly 2.54 centimeters make one inch.

Updated October 30, 2026 · How we check facts

The centimeter (cm) is the SI prefix "centi" (10⁻²) applied to the meter: 100 cm make 1 m. NIST lists the inch as exactly 2.54 cm, which links the metric and US customary length scales.

Conversion

cm = in × 2.54
in = cm ÷ 2.54
cm = m × 100

Example

A 30 cm ruler is 30 ÷ 2.54 = 11.81 inches. A height of 180 cm is 180 ÷ 2.54 = 70.87 inches, or 5 ft 10.9 in. Use inches to cm or cm to feet for other values; the metric vs imperial guide and how to read a tape measure show both scales.

Common mistakes

A centimeter is 10 millimeters (millimeter), not 100. The 2.54 factor is exact, so no rounding is needed when converting inches to centimeters.

Calculate it

Free toolInches to CM ConverterInches to cm, cm to inches and height in feet.Open →Free toolCM to Feet ConverterCentimeters to feet and inches, for heights.Open →

Guides that explain it

Related terms

Meter (m)The meter is the SI base unit of length; exactly 100 centimeters, about 3.2808 feet, 39.37 inches or 1.0936 yards; the international foot is defined from it.Inch (in)The inch is a unit of length equal to exactly 2.54 centimeters (0.0254 m); 12 inches make a foot and 36 make a yard; a meter is 39.37 inches.Millimeter (mm)The millimeter is a metric unit of length equal to one thousandth of a meter (0.001 m); there are exactly 25.4 millimeters in one inch.Fluid Ounce (fl oz)A fluid ounce is a unit of volume; one US fluid ounce is 29.57353 milliliters, and 8 of them make a US cup. It is not the same as the ounce used to weigh things.Gram (g)The gram is a metric unit of mass equal to one thousandth of a kilogram, the SI base unit of mass; about 0.03527 ounces.Imperial GallonThe imperial gallon, used in the UK and in Canadian measures, is exactly 4.54609 liters, about 20% larger than the US gallon (3.785412 L).International FootThe international foot is the standard foot of 0.3048 meters exactly; it replaced the US survey foot for all uses from 1 January 2023, apart from historic data.Kilogram (kg)The kilogram is the SI base unit of mass, equal to 1,000 grams and about 2.2046 pounds; it is the only base unit whose name carries a prefix.

Sources