Reference table

Typography: points, picas, millimetres and pixels

Print and web use different points. A DTP point is 1/72 inch and a CSS pixel is 1/96 inch. The table shows the same type size in every unit.

Typography: points, picas, millimetres and pixels
ptpxmmpc
11.33333333 px0.35277778 mm0.08333333 pc
68 px2.11666667 mm0.5 pc
810.66666667 px2.82222222 mm0.66666667 pc
912 px3.175 mm0.75 pc
1013.33333333 px3.52777778 mm0.83333333 pc
1114.66666667 px3.88055556 mm0.91666667 pc
1216 px4.23333333 mm1 pc
1418.66666667 px4.93888889 mm1.16666667 pc
1824 px6.35 mm1.5 pc
2432 px8.46666667 mm2 pc
3648 px12.7 mm3 pc
7296 px25.4 mm6 pc

12 pt make one pica and 72 pt make one inch. On the web 1 px is defined as 1/96 inch, so 12 pt equals 16 px there. That 16 px only holds at 100 percent zoom: browsers scale type independently and the system setting can change the base size. The inch relation (1 in = 25.4 mm) comes from the unit system, while the point definitions come from print and the CSS specification.

Sources

W3C CSS Values and UnitsDefinition of the CSS pixel as 1/96 inch and of the CSS length units.NIST Guide to SI Appendix BNIST conversion-factor method and non-SI factors.

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