Print units
Convert px, mm, cm and inches at a given DPI
25.4 mm = 96 px
Ratio: 96 px ÷ 25.4 mm = 3.7795 px/mm
Convert millimetres to pixels and back at a given resolution. Essential as soon as a file meant for print has to be prepared on screen, or a physical size has to be respected.
How it works
The conversion depends entirely on resolution, expressed in dots per inch. One inch is 25.4mm, which gives the number of pixels per millimetre directly. Without a DPI figure, a size in pixels matches no physical dimension at all.
px = mm × DPI ÷ 25.4 mm = px × 25.4 ÷ DPI
Common values
| mm | 300 DPI |
|---|---|
| 10 mm | 118 px |
| 20 mm | 236 px |
| 50 mm | 591 px |
| 100 mm | 1181 px |
| 148 mm | 1748 px |
| 210 mm | 2480 px |
| 297 mm | 3508 px |
Frequently asked questions
Which resolution should I pick?
300 DPI for quality printing, 150 DPI for everyday output or a proof, 72 or 96 DPI for screen only. A professional printer will usually ask for 300 DPI at final size.
Why does my image look sharp on screen and blurry in print?
Because a screen shows around 96 DPI while print asks for 300. An 800px wide image spans 21cm on screen but only 6.8cm printed at 300 DPI without quality loss.
Does DPI change the file size?
No. File size depends on the pixel count and the compression. DPI is only metadata telling the printer at what physical size those pixels should be rendered.