Unit Converter / Millimeters to Centimeters
Millimeters to Centimeters Converter
1 millimeter = 0.1 centimeters at 96 DPI, the CSS reference resolution. To convert, multiplymillimeters by 0.1: mm × 0.1 = cm. Change the DPI below for print and image work, where a pixel is whatever the output resolution says it is.
Millimeters to Centimeters table
Standard values at 96 DPI.
| Millimeters (mm) | Centimeters (cm) |
|---|---|
| 1 | 0.1 |
| 5 | 0.5 |
| 10 | 1 |
| 25.4 | 2.54 |
| 50 | 5 |
| 100 | 10 |
| 210 | 21 |
| 254 | 25.4 |
| 297 | 29.7 |
How the conversion works
The fine metric unit: print tolerances, paper (A4 is 210 by 297 mm) and CSS print stylesheets use millimeters. Exactly 25.4 mm make an inch. The metric print unit outside the US: A4 paper is 21 by 29.7 centimeters. One centimeter is exactly 0.3937 inches. The CSS specification anchors the whole system to the inch: at the reference resolution of 96 DPI, one inch is exactly 96 pixels, one point is 96/72 pixels, and the metric units follow from the inch being exactly 25.4 millimeters. Converting millimeters to centimeters therefore goes through that anchor: millimeters to pixels, then pixels to centimeters. For example,100 mm = 10 cm.
The DPI setting matters only when pixels meet the physical world. On screen, CSS pixels are defined by the 96 DPI reference and the conversion above is exact. In a 300 DPI print file or image, an inch holds 300 pixels instead, so the same measurement converts differently; set the resolution to match the file you are working with.