Unit Converter / Pixels to Millimeters

Pixels to Millimeters Converter

1 pixel = 0.2646 millimeters at 96 DPI, the CSS reference resolution. To convert, multiplypixels by 0.2646: px × 0.2646 = mm. Change the DPI below for print and image work, where a pixel is whatever the output resolution says it is.

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Pixels to Millimeters table

Standard values at 96 DPI.

Pixels (px)Millimeters (mm)
10.2646
82.1167
123.175
164.2333
246.35
10026.4583
20052.9167
500132.2917
720190.5
1080285.75
1920508

How the conversion works

The screen unit. CSS defines the reference pixel so that 96 px make one inch at arm's-length viewing distance. 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 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 pixels to millimeters therefore goes through that anchor: pixels to pixels, then pixels to millimeters. For example,100 px = 26.4583 mm.

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 pixel count converts differently; set the resolution to match the file you are working with.

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