Millimeters to Centimeters Converter
Type a length in millimeters and the equivalent in centimeters appears at once, rounded to four decimal places. The guide below explains the rule and lists common values.
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Created by the Reeliy Editorial Team. Last updated: Oct 19, 2026
How many millimeters are in a centimeter?
A centimeter contains exactly 10 millimeters. Both are metric units of length, written cm and mm, and both are named from the meter: a millimeter is one thousandth of a meter and a centimeter is one hundredth of a meter. Dividing one by the other gives the ratio of ten to one.
1 cm = 10 mm 1 mm = 0.1 cmThe factor is an exact power of ten, so no rounding is involved in the definition.
Because the factor is 10, converting between the two units never needs a calculator: you only shift the decimal point one place.
Millimeters and centimeters compared
The millimeter is the small division you see on a ruler. It suits thin or precise things: the thickness of a bank card is about 0.76 mm, a screw diameter is quoted in millimeters, and engineering drawings usually dimension parts in mm. The centimeter is roughly the width of a fingertip and is the natural unit for body measurements, clothing sizes, shelf spacing and the size of small objects.
Mixed documents are where the conversion earns its keep. A product page may list a length in centimeters while the technical sheet gives millimeters, and a sewing pattern may switch between the two. A4 paper, for instance, is 210 × 297 mm, which is the same as 21 × 29.7 cm.
How to convert mm to cm
centimeters = millimeters ÷ 10
- Enter the length in millimeters in the top box.
- Read the length in centimeters from the lower box; it updates on every keystroke.
- To do it by hand, divide by 10, which is the same as moving the decimal point one place to the left.
Worked examples
A sheet of A4. The long side is 297 mm. 297 ÷ 10 = 29.7 cm.
A bolt. A bolt measures 18.5 mm under the head. 18.5 ÷ 10 = 1.85 cm.
Going the other way. A phone case listed as 6.4 cm wide is 6.4 × 10 = 64 mm wide. The centimeters to millimeters converter handles that direction directly.
Millimeters to centimeters conversion table
| Millimeters (mm) | Centimeters (cm) |
|---|---|
| 1 | 0.1 |
| 2 | 0.2 |
| 5 | 0.5 |
| 10 | 1 |
| 15 | 1.5 |
| 25 | 2.5 |
| 50 | 5 |
| 75 | 7.5 |
| 100 | 10 |
| 250 | 25 |
| 500 | 50 |
| 1,000 | 100 |
Precision and limits of this converter
The answer is rounded to four decimal places, which is a resolution of one thousandth of a millimeter. That is more than enough for rulers, tape measures and workshop drawings. Lengths far below that, such as 0.00004 mm, show as 0 cm; for sizes that small switch to the millimeters to micrometers converter or the millimeters to nanometers converter.
For larger units use millimeters to meters, and for imperial sizes use millimeters to inches. More length tools are listed under dimension converters.
Frequently asked questions
How do I convert mm to cm?
Divide the number of millimeters by 10. For example, 85 mm ÷ 10 = 8.5 cm.
How many millimeters are in 1 cm?
There are exactly 10 millimeters in one centimeter.
Which is bigger, a millimeter or a centimeter?
A centimeter is ten times longer than a millimeter. One millimeter is 0.1 cm.
How do I convert centimeters to millimeters?
Multiply the centimeters by 10, or move the decimal point one place to the right. For instance, 3.2 cm is 32 mm.
References
Cite this converter and page
If you use this page in your work, you can cite it as:
Reeliy Editorial Team. (2026). Millimeters to Centimeters Converter. Reeliy. https://reeliy.com/converters/convert-mm-to-cm-millimeters-to-centimeters“Millimeters to Centimeters Converter.” Reeliy, 2026, https://reeliy.com/converters/convert-mm-to-cm-millimeters-to-centimeters.