CSS Unit Converter
Convert between px, rem, em, pt and percent.
1 remHow to use
- 1 Enter the value you want to convert.
- 2 Pick the unit you are converting from and to.
- 3 Set the base font size if it is not 16px.
- 4 Read and copy the converted result.
About CSS Unit Converter
The CSS Unit Converter translates a length between the units you use in stylesheets: pixels, rem, em, points and percent.
Set a base font size (16px by default) and rem, em and percent are resolved against it, while points use the standard CSS convention where 1pt equals roughly 1.333px (96 over 72).
Change any field and the result updates immediately.
Modern CSS leans on rem for accessible, scalable typography, but design specs and legacy code are still full of pixels and points.
Converting in your head is fiddly and error-prone, especially once a non-default root font size is in play.
This tool makes the relationship explicit: type 24px and see 1.5rem, or set the base to 20 and watch the rem value shift.
It is useful when migrating a pixel-based design system to rem, matching a print-style point size to screen pixels, or sanity-checking a percentage relative to a parent.
Invalid input — a non-numeric value, an unknown unit or a zero base size — produces a clear message rather than a misleading number.
The maths runs entirely in your browser, with nothing sent over the network.
FAQ
How is a point (pt) defined here?
It uses the CSS convention of 96dpi, so 1pt equals about 1.333px (96 ÷ 72). That matches how browsers render pt.
What does the base font size affect?
It is the reference for rem, em and percent. Changing it rescales those conversions; px and pt are unaffected.