cm to mm Converter

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Convert centimeters to millimeters using the SI relation 1 cm = 10 mm. Common when reading European clothing sleeve length to feed into a millimeter-precise pattern, or when converting carpentry measurements between rulers calibrated in different sub-divisions. The math runs locally in your browser.

Centimeter (cm)
Millimeter (mm)

Centimeter (cm) → Millimeter (mm)

Quick reference table

Centimeter (cm)Millimeter (mm)
1 cm10 mm
2 cm20 mm
5 cm50 mm
10 cm100 mm
25 cm250 mm
50 cm500 mm
100 cm1000 mm

Glossary

Centimeter (cm)

A centimeter is one hundredth of a meter (1 cm = 10 mm = 0.3937 inch). It is the everyday metric unit for clothing sizes, body measurements, paper formats and small object dimensions. Two and a half centimeters approximate one inch; ninety-one centimeters approximate one yard.

Millimeter (mm)

A millimeter is one thousandth of a meter (1 mm = 0.1 cm = 0.03937 inch). It is the default fine-resolution unit on rulers, mechanical drawings, electronics PCBs and rainfall gauges. Ten millimeters make a centimeter; one inch contains exactly 25.4 millimeters by international agreement since 1959.

Metric system (SI)

The metric system is a decimal system of measurement built around the meter for length, the kilogram for mass and the second for time, with multiples and submultiples expressed as powers of ten (millimeter, centimeter, kilometer). Adopted in France in 1799 and codified internationally as the International System of Units (SI) in 1960, it is now the official measurement system in nearly every country and the standard in science and engineering worldwide.

Imperial / US Customary system

The imperial system is the historical English system of weights and measures whose length units are the inch, foot, yard and mile (12 in = 1 ft, 3 ft = 1 yd, 1,760 yd = 1 mi). Codified by the British Weights and Measures Act of 1824 and aligned with US Customary by the international yard-and-pound agreement of 1959 (1 inch = 25.4 mm exactly), it is still used in the United States, the United Kingdom and a handful of other countries for everyday distances.

Related tools

Millimeters to Centimeters
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Convert centimeters to inches — exact factor 1 cm = 0.3937 in
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Convert length units between metric and imperial — mm, cm, m, km, inches, feet, yards, miles