Convert Centimeters to Millimeters
Centimeters to millimeters is one of the simplest metric conversions there is — both units share the same base-ten system. One centimeter is exactly 10 millimeters.
Centimeters to Millimeters conversion table
| Centimeters (cm) | Millimeters (mm) |
|---|---|
| 1 | 10 |
| 2 | 20 |
| 3 | 30 |
| 5 | 50 |
| 10 | 100 |
| 20 | 200 |
| 50 | 500 |
| 100 | 1,000 |
| 500 | 5,000 |
| 1,000 | 10,000 |
The formula
To convert centimeters to millimeters, multiply the length in centimeters by 10:
millimeters = centimeters × 10
A worked example
Converting 100 cm into millimeters:
100 × 10 = 1,000 mm
The same scaling applies at smaller values: 10 cm is 100 mm, and 5 cm is 50 mm.
When you'll use it
Reading precise measurements on a ruler, converting a part dimension for manufacturing or 3D printing, or double-checking a spec sheet that mixes centimeters and millimeters. Because the factor is a clean 10, this is one of the easiest conversions to do without a calculator.
Frequently asked questions
How many millimeters are in a centimeter?
Exactly 10 millimeters. This is exact by definition, since the metric system defines a centimeter as 10 millimeters with no rounding.
Is the centimeter to millimeter conversion exact?
Yes, always. Both units come from the same metric base, so converting between them is just multiplying or dividing by 10 — there's no approximation involved.
How do I convert centimeters to millimeters in my head?
Move the decimal point one place to the right, or just multiply by 10. 7.5 cm becomes 75 mm, 12 cm becomes 120 mm.