CM to MM Converter
Quick answer: To convert CM to MM, multiply by 10. For example, 10 cm is 100 mm. One centimeter equals 10 mm.
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Use the CM to MM Converter
CM to MM formula and what each symbol means
mm = cm × 10
| Symbol | Meaning |
|---|---|
| cm | Centimeter |
| mm | Millimeter |
CM to MM examples
1 cm
1 cm × 10 = 10 mm.
10 cm
10 cm × 10 = 100 mm.
100 cm
100 cm × 10 = 1,000 mm.
CM compared with MM
One cm is 10 times as large as one mm, so your number gets bigger when you convert CM to MM and smaller when you convert back. If the answer is not larger than what you typed, you divided instead of multiplying.
About CM and MM
Centimeter (cm): One hundredth of a metre. Millimeter (mm): One thousandth of a metre.
Where CM to MM conversions are used
Sports, aviation and shipping each keep their own favourites: yards on a football pitch, feet for altitude, nautical miles at sea. Road distances and maps use kilometres or miles, while building plans use metres, millimetres or feet.
How to calculate CM to MM step by step
- Enter the value in cm (the starting unit).
- Multiply by 10, because 1 cm = 10 mm.
- The product is the value in mm. To go back, divide by 10 or multiply by 0.1.
Popular length conversions
How to read your CM to MM result
Between metric and imperial, the key fact is that 1 inch is exactly 2.54 cm, which makes 1 foot exactly 0.3048 m, 1 yard exactly 0.9144 m and 1 mile exactly 1,609.344 m.
| CM | MM |
|---|---|
| 1 | 10 |
| 2 | 20 |
| 5 | 50 |
| 10 | 100 |
| 20 | 200 |
| 50 | 500 |
| 100 | 1,000 |
| 1,000 | 10,000 |
MM to CM: quick table
| MM | CM |
|---|---|
| 1 | 0.1 |
| 5 | 0.5 |
| 10 | 1 |
| 25 | 2.5 |
| 50 | 5 |
| 100 | 10 |
| 250 | 25 |
| 500 | 50 |
Common mistakes when calculating CM to MM
- Rounding the factor too early, for example using 2.5 instead of 2.54 for inches.
- Dividing when you should multiply: from cm to mm multiply by 10; from mm to cm divide by 10.
CM to MM FAQ
How many mm are in 1 cm?
1 cm equals 10 mm.
How many cm are in 1 mm?
1 mm equals 0.1 cm.
Is 1 cm = 10 mm an exact conversion?
Yes. The centimeter and the millimeter are both defined exactly in SI terms, so the ratio has no measurement uncertainty; 10 is just that ratio shown to 7 significant figures.
What is a millimeter (mm)?
One thousandth of a metre.
How can I estimate CM to MM in my head?
One cm is 10 times as large as one mm, so your number gets bigger when you convert CM to MM and smaller when you convert back. If the answer is not larger than what you typed, you divided instead of multiplying.
What is 75 cm in MM?
75 cm = 750 mm (since 75 × 10).
What is 300 cm in MM?
300 cm = 3,000 mm (since 300 × 10).
What is 12 cm in MM?
12 cm = 120 mm (since 12 × 10).
How many decimals should I keep when converting cm to mm?
Match the precision of your original measurement. For example, 100 mm rounds to 100 mm at 3 significant figures; keep more digits only for engineering or scientific work.
More in Length converters
- Feet to Inches Converter
- CM to KM Converter
- Feet to KM Converter
- CM to Inches Converter
- Feet to Meters Converter
- CM to Feet Converter
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Method, review and disclaimer
Edited by: Hemant Kumar and Anjita Rai, founders of ToolsVault (SEO and content professional, not a licensed adviser). Method: this tool runs in your browser using the formula shown on this page; the numbers you enter are not sent to our servers. Sources: NIST SP 811, Appendix B.8: conversion factors, BIPM: the SI base units