Centimeters to millimeters
1 cm equals 10 mm. Convert centimeters to millimeters or back, with worked examples for measuring and checking dimensions.
Enter your values, then calculate.
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The formula, explained
cm × 10 = mmThe factor is fixed. Reverse the direction to convert back. Rounding is applied only to the displayed result.
An example to check
Using the starting values below, the calculation gives:
Common conversions
| cm | mm |
|---|---|
| 1 | 10 |
| 2 | 20 |
| 5 | 50 |
| 10 | 100 |
| 25 | 250 |
| 50 | 500 |
| 100 | 1,000 |
How to use this tool
- Choose “cm → mm” and enter a length in centimeters. Multiply by 10: 1 cm = 10 mm.
- Choose “mm → cm” to enter a length in millimeters instead. Divide by 10: 1 mm = 0.1 cm.
Converting DIY or sewing measurements
A width of 3.5 cm is 3.5 × 10 = 35 mm. In the other direction, 125 mm ÷ 10 = 12.5 cm. For a small thickness, 0.8 mm = 0.08 cm: converting to centimeters does not mean rounding to a whole centimeter.
On a ruler marked in millimeters, each of the ten intervals between consecutive centimeter marks represents 1 mm. For an object with both a width and a height, convert each measurement separately and keep the units consistent: a piece measuring 3.5 × 12.5 cm measures 35 × 125 mm.
Centimeters and square centimeters are different
The ×10 factor applies to length. For area, square it: 1 cm² = 100 mm². For volume, 1 cm³ = 1,000 mm³. Use the metric conversion table and select “Area” or “Volume” for these measurements.
The unit conversion is exact, but it cannot improve the accuracy of your original measurement. Keep useful decimal places during the calculation and round only as much as your task requires.
Reference: NIST — SI prefixes, centi and milli ↗.
Can I use a decimal comma?
Yes. Numeric fields accept 12.5 or 12,5 and spaces for thousands, such as 1 234.50. Do not mix a point and comma in one number.
Where are my inputs processed?
Calculations run in your browser. Form values are not sent to Analytics. Copying, printing, sharing or opening an external service is your choice.
Method and interface checked on 2026-10-22 · Report an error