Millimeters to Centimeters Converter (mm to cm)
10 mm = 1 cm exactly. Convert millimeters to centimeters by moving the decimal point, with charts for paper sizes, photos, bricks and cards.
Centimeter (cm) = Millimeter (mm) × 0.1
Millimeter (mm): The millimetre is one thousandth of a metre (0.001 m). There are 10 millimetres in a centimetre, and exactly 25.4 millimetres in an international inch.
Centimeter (cm): The centimetre is one hundredth of a metre (0.01 m). It is used for everyday measurements such as body height, clothing and paper sizes, and one inch is exactly 2.54 cm.
| Millimeter (mm) | Centimeter (cm) |
|---|---|
| 1 | 0.1 |
| 5 | 0.5 |
| 10 | 1 |
| 25 | 2.5 |
| 50 | 5 |
| 100 | 10 |
Engineering drawings, paper sizes, photo specifications and furniture catalogs give dimensions in millimeters, while rulers, sewing patterns and many product labels speak in centimeters. A centimeter is ten millimeters, so the conversion only moves the decimal point one place to the left.
Millimeters are the default in technical work because they avoid decimals: a kitchen plan marks a 2.4 m wall as 2400, and an A4 sheet is 210 × 297 mm. Converting is mostly about reading such numbers against a ruler marked in centimeters, or filling in a form that asks for cm.
How to use this tool
- Type a value in the Millimeter box to see it in centimeters, or type in the Centimeter box to convert the other way.
- Press ⇄ to swap the two units, or Load example for a typical value.
- Check the charts below for common values; for other units, open the Length converter.
Formula
Centimeter (cm) = Millimeter (mm) × 0.1
Millimeter (mm) = Centimeter (cm) × 10
Both factors come from exact definitions: 1 centimeter = 10 millimeters and 1 millimeter = 0.1 centimeters (shown to 12 significant digits).
Example
Two conversions worked with the same factors the converter uses:
297 mm × 0.1 = 29.7 cm
8.5 cm × 10 = 85 mm
Millimeter to Centimeter chart
Common values from millimeters to centimeters, rounded to four decimal places.
| Millimeter (mm) | Centimeter (cm) |
|---|---|
| 1 | 0.1 |
| 2 | 0.2 |
| 2.5 | 0.25 |
| 4 | 0.4 |
| 5 | 0.5 |
| 7.5 | 0.75 |
| 9 | 0.9 |
| 12 | 1.2 |
| 15 | 1.5 |
| 18 | 1.8 |
| 25 | 2.5 |
| 35 | 3.5 |
| 45 | 4.5 |
| 60 | 6 |
| 70 | 7 |
| 85 | 8.5 |
| 99 | 9.9 |
| 125 | 12.5 |
| 148 | 14.8 |
| 175 | 17.5 |
| 210 | 21 |
| 297 | 29.7 |
| 420 | 42 |
| 500 | 50 |
| 1,000 | 100 |
Centimeter to Millimeter chart
The reverse direction for values people often look up.
| Centimeter (cm) | Millimeter (mm) |
|---|---|
| 0.1 | 1 |
| 0.5 | 5 |
| 1 | 10 |
| 1.5 | 15 |
| 2 | 20 |
| 3 | 30 |
| 4.5 | 45 |
| 6 | 60 |
| 8 | 80 |
| 12 | 120 |
| 20 | 200 |
| 25 | 250 |
| 50 | 500 |
| 100 | 1,000 |
Sizes usually written in millimeters
| Item | Millimeter (mm) | Centimeter (cm) |
|---|---|---|
| Passport photo width (many countries) | 35 | 3.5 |
| Passport photo height (many countries) | 45 | 4.5 |
| A5 paper, long side | 210 | 21 |
| A3 paper, long side | 420 | 42 |
| UK standard brick, length | 215 | 21.5 |
| UK standard brick, height | 65 | 6.5 |
| Bank card, long side (ISO/IEC 7810 ID-1) | 85.6 | 8.56 |
| Euro pallet, long side | 1,200 | 120 |
| A6 paper (postcard size), short side | 105 | 10.5 |
Quick mental estimate
Move the decimal point one place to the left: 420 mm → 42 cm and 85.6 mm → 8.56 cm. Nothing is rounded, so keep every digit; dropping the last one changes the size by up to half a millimeter. To go back to millimeters, move the point one place to the right.
Use the converter or the charts when the exact figure matters.
The two units
Millimeter (mm): The millimetre is one thousandth of a metre (0.001 m). There are 10 millimetres in a centimetre, and exactly 25.4 millimetres in an international inch.
Centimeter (cm): The centimetre is one hundredth of a metre (0.01 m). It is used for everyday measurements such as body height, clothing and paper sizes, and one inch is exactly 2.54 cm.
Frequently asked questions
How many centimeters is 1 mm?
Exactly 0.1 cm. The smallest marks on a centimeter ruler are usually millimeters, ten between each numbered centimeter.
What size is a passport photo in cm?
The common 35 × 45 mm format is 3.5 × 4.5 cm. Check the issuing country's rules, since the US uses a 2 × 2 inch photo (51 × 51 mm) instead, and some countries set sizes of their own.
Is rainfall of 10 mm the same as 1 cm?
Yes. Rain gauges report depth, so 10 mm of rain is a layer of water 1 cm deep over flat ground. That depth also equals 10 liters on every square meter, which is how rain totals connect to water volume.
How precise is the result?
The converter uses the exact definitions above with browser floating-point arithmetic and shows up to 12 significant digits. The charts round to four decimal places for reading.
Sources
Last updated:
Page address with these inputs: https://kakao.mobile/tools/millimeter-to-centimeter-converter/
Cite or embed this tool
kakaoCalc. (2026, November 8). Millimeters to Centimeters Converter (mm to cm). https://kakao.mobile/tools/millimeter-to-centimeter-converter/
“Millimeters to Centimeters Converter (mm to cm).” kakaoCalc, 8 Nov. 2026, kakao.mobile/tools/millimeter-to-centimeter-converter/.
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