Centimeters to Millimeters
Type a value in either box to convert between centimeters and millimeters. The factor is 10.
| Centimeters | Millimeters |
|---|---|
| 1 cm | 10 mm |
| 2 cm | 20 mm |
| 3 cm | 30 mm |
| 5 cm | 50 mm |
| 10 cm | 100 mm |
| 25 cm | 250 mm |
| 50 cm | 500 mm |
| 100 cm | 1000 mm |
How to use
- Enter a value in the Centimeters field.
- The Millimeters figure appears immediately — no button to press.
- Typing in the Millimeters field converts back to Centimeters the same way.
- Use the reference table for the values that come up most often.
Centimeters to Millimeters formula
The factor from centimeters to millimeters is 10.
mm = cm × 10
Put another way, one centimeter is exactly 10 millimeters.
Why this factor: the centimeter and the millimeter are both defined against the meter, so dividing one definition by the other gives 10 directly. Both definitions are set out in full below.
To go the other way, divide by 10 — or use the Millimeters to Centimeters converter, which is the same calculation reversed.
Worked example
Given 12 cm, multiplying by 10 yields 120 mm.
12 cm × 10 = 120 mm
The converter above does this for any value you type, in either direction.
What is a centimeter?
A centimeter is one hundredth of a meter, the everyday metric unit for body and object measurements.
Definition: Exactly 0.01 meter by SI prefix definition.
Where it is used: Height, clothing sizes, rainfall, paper and screen dimensions across the metric world.
What is a millimeter?
A millimeter is one thousandth of a meter — the working precision unit of manufacturing and construction.
Definition: Exactly 0.001 meter by SI prefix definition.
Where it is used: Engineering drawings, machining tolerances, timber and steel dimensions, rainfall totals.
Centimeters vs Millimeters
The centimeter and the millimeter belong to the same family of units, so converting between them is usually a matter of shifting a decimal point or applying a small whole-number factor.
Frequently asked questions
How many millimeters are in a centimeter?
One centimeter equals 10 millimeters.
What is the formula to convert centimeters to millimeters?
Multiply the number of centimeters by 10. To reverse it, divide by 10 instead.
How do I convert millimeters back to centimeters?
Divide by 10, which is the same as multiplying by 0.1.
How many millimeters are in 10 centimeters?
10 cm works out to 100 mm.
How is the centimeter defined?
Exactly 0.01 meter by SI prefix definition.