Pixels to MM Converter
Convert px to mm at whatever density you are working to. Millimetres are the working unit for most print specifications outside North America, so this is the conversion European and Asian print jobs need.
Type in either field — the other one follows instantly.
How to convert pixels to millimetres
Convert to inches first, then scale: mm = (pixels ÷ PPI) × 25.4. There are exactly 25.4 millimetres in an inch, so the arithmetic is precise rather than approximate.
At 300 DPI one millimetre is 11.811 pixels, so a 210 mm A4 page is 2480 pixels wide. At the 96 PPI screen standard the same millimetre is only 3.7795 pixels.
Worked with the values in the calculator above
mm = 2,480 px ÷ 300 PPI × 25.4 = 210 mm
pixels = 210 mm ÷ 25.4 × 300 PPI = 2,480 px Millimetres in print specifications
ISO paper sizes are defined in millimetres: A4 is exactly 210 × 297 mm, A3 is 297 × 420 mm. Converting from those defining numbers rather than from rounded inch equivalents avoids the one-pixel drift that shows up when you tile or add bleed.
Standard bleed is 3 mm on each edge, which is 35 pixels at 300 DPI. An A4 artboard with bleed is therefore 2551 × 3579 pixels rather than 2480 × 3508.
Reference table
| Pixels | 72 DPI | 96 DPI | 150 DPI | 300 DPI |
|---|---|---|---|---|
| 1 px | 0.353 mm | 0.265 mm | 0.169 mm | 0.085 mm |
| 10 px | 3.53 mm | 2.65 mm | 1.69 mm | 0.85 mm |
| 100 px | 35.28 mm | 26.46 mm | 16.93 mm | 8.47 mm |
| 500 px | 176.39 mm | 132.29 mm | 84.67 mm | 42.33 mm |
| 1000 px | 352.78 mm | 264.58 mm | 169.33 mm | 84.67 mm |
| 2480 px | 874.89 mm | 656.17 mm | 419.95 mm | 209.97 mm |
| 3508 px | 1237.72 mm | 928.29 mm | 594.11 mm | 297.05 mm |
Frequently asked questions
How many pixels are in a millimetre at 300 DPI?
One millimetre is 11.811 pixels at 300 DPI, because 300 pixels cover 25.4 mm. At 96 PPI the same millimetre is 3.7795 pixels.
How do I convert pixels to mm?
Divide the pixels by the density to get inches, then multiply by 25.4: mm = (pixels ÷ PPI) × 25.4.
How many pixels is A4 in millimetres?
A4 is 210 × 297 mm, which is 2480 × 3508 pixels at 300 DPI and 1240 × 1754 pixels at 150 DPI.
How many pixels wide is an A4 page in millimetres terms?
A4 is 210 mm across, which is 2480 pixels at 300 DPI and 794 pixels at 96 PPI. Convert the millimetres to inches first, then multiply by the density.