Convert centimeters to millimeters
1 cm = 10 mm · Formula and table below. Converting the other way? Millimeters to Centimeters →
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Other units
- Meter (m) 0.01
- Kilometer (km) 0.00001
- Decimeter (dm) 0.1
- Centimeter (cm) 1
- Millimeter (mm) 10
- Micrometer (µm) 10,000
- Nanometer (nm) 10,000,000
- Mile (mi) 0.000006214
- Yard (yd) 0.010936133
- Foot (ft) 0.032808399
- Inch (in) 0.393700787
- Nautical mile (nmi) 0.0000054
- Light year (ly) 1.057001×10⁻¹⁸
Reviewed on by the Skala Convert team
Multiply centimetres by 10. A 2.5 cm button is 25 mm.
How many millimeters in a centimeter?
mm = cm × 10
On a metric ruler this is visible: each centimetre is divided into ten small marks, each one a millimetre. The long marks are centimetres, the medium mark in the middle is 5 mm.
Why convert centimeters to millimeters at all?
Millimetres remove the decimal point, and that matters when a measurement is read aloud, typed or written on a cutting list. "Nine point five centimetres" is easily heard as 9.5 or 95; "ninety-five millimetres" is not. Trades that work to fine tolerances — joinery, jewellery, printing — standardise on millimetres for that reason.
How are millimeters used in sewing and jewelry?
- A standard seam allowance of 1.5 cm is 15 mm; in the US it is 5/8 in, which is 15.9 mm
- Ring sizes are defined by inner diameter or circumference in millimetres; a ring with an inner diameter of 1.7 cm is 17 mm
- Beads and buttons are sold by diameter in millimetres
For the reverse step, see mm to cm.
Why is the factor exactly 10?
Because both units are the metre with a prefix, and the SI Brochure published by the International Bureau of Weights and Measures (BIPM) fixes centi at a hundredth and milli at a thousandth. ISO 129-1 lets a technical drawing state one predominant unit and omit it from each dimension; in mechanical engineering that unit is almost always the millimetre, the usual reason a centimetre measurement has to be converted at all.
Formula
Millimeters = Centimeters × 10
10 cm = 100 mm
Conversion table
| cm | mm |
|---|---|
| 1 | 10 |
| 2 | 20 |
| 5 | 50 |
| 10 | 100 |
| 20 | 200 |
| 25 | 250 |
| 50 | 500 |
| 100 | 1000 |
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Frequently asked questions
How many mm is 1 cm?
10 mm.
What is 1.5 cm in mm?
15 mm.
Why do engineers use mm instead of cm?
Millimetres avoid decimal points, which reduces reading and transcription errors.