ucUnitCloudInternational unit matrix

Mistake guide

Equating points and pixels

A type size of 12 pt corresponds to 12 px.

01Assumption

A type size of 12 pt corresponds to 12 px.

02Actually

On the web 12 pt is 16 px, not 12. The reason is two different inch references: a DTP point is 1/72 inch, a CSS pixel 1/96 inch. The ratio is 96/72, that is 1.3333.

03Why

In print the point was the only relevant type measure for decades. For the web the pixel was fixed at 1/96 inch so that type appears the same size on different screens. Both units denote a length, but with a different reference.

04Check

To convert points to pixels multiply by 4/3. That value only holds at 100 percent zoom and with an unchanged system setting — browsers and operating systems can scale the base size, and the system font-size setting changes it as well.

Matching conversions

Point to CSS pixelpt → pxTypographyCSS pixel to Pointpx → ptTypographyPoint to Millimetrept → mmTypographyMillimetre to Pointmm → ptTypography

Matching tables

TableTypography: points, picas, millimetres and pixels

Unit family: Typography

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.
When not to use

Do not use as the sole basis for official, medical, safety-critical or contractual decisions.

Citation

Citation note: UnitCloud, mistake guide, sources reviewed: September 2026. Source basis: W3C CSS Values and Units · NIST Guide to SI Appendix B.