Formula
mm = px × 25.4 ÷ 96
16px = 4.2333mm. CSS defines this ratio as fixed.
For CSS absolute units this is exact. For a real print job you want the DPI-based conversion instead — the two answer different questions.
Converter
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px to mm conversion table
| px | mm | Rounded |
|---|---|---|
| 1px | 0.26458mm | 0.26mm |
| 2px | 0.52917mm | 0.53mm |
| 4px | 1.05833mm | 1.06mm |
| 6px | 1.5875mm | 1.59mm |
| 8px | 2.11667mm | 2.12mm |
| 10px | 2.64583mm | 2.65mm |
| 12px | 3.175mm | 3.17mm |
| 14px | 3.70417mm | 3.7mm |
| 16px | 4.23333mm | 4.23mm |
| 18px | 4.7625mm | 4.76mm |
| 20px | 5.29167mm | 5.29mm |
| 22px | 5.82083mm | 5.82mm |
| 24px | 6.35mm | 6.35mm |
| 28px | 7.40833mm | 7.41mm |
| 32px | 8.46667mm | 8.47mm |
| 36px | 9.525mm | 9.52mm |
| 40px | 10.58333mm | 10.58mm |
| 44px | 11.64167mm | 11.64mm |
| 48px | 12.7mm | 12.7mm |
| 56px | 14.81667mm | 14.82mm |
| 64px | 16.93333mm | 16.93mm |
| 72px | 19.05mm | 19.05mm |
| 80px | 21.16667mm | 21.17mm |
| 96px | 25.4mm | 25.4mm |
| 112px | 29.63333mm | 29.63mm |
| 128px | 33.86667mm | 33.87mm |
| 144px | 38.1mm | 38.1mm |
| 160px | 42.33333mm | 42.33mm |
| 192px | 50.8mm | 50.8mm |
| 224px | 59.26667mm | 59.27mm |
| 256px | 67.73333mm | 67.73mm |
| 320px | 84.66667mm | 84.67mm |
| 384px | 101.6mm | 101.6mm |
| 448px | 118.53333mm | 118.53mm |
| 512px | 135.46667mm | 135.47mm |
Questions
How do I convert px to mm?
mm = px × 25.4 ÷ 96. So 16px = 4.2333mm.
Is the px to mm conversion exact?
Yes, for CSS. The specification fixes 1in = 96px, which pins every absolute unit to a fixed ratio regardless of the physical display. It is not a physical measurement — a CSS inch on a phone is not an inch of glass. For real-world output size use the DPI calculator instead.
How do I convert mm back to px?
Invert the formula, or use the mm to px converter.
Other conversions
Conversions follow the CSS Values and Units specification, in which 1in is defined as exactly 96px. Values are computed, not tabulated by hand.