CSS Units Converter
Free CSS units converter. Convert between px, rem, em, pt, pc and physical units based on root font size. For responsive design and CSS workflows.
Runs in your browserUpdated Apr 26, 2026
CSS units converter
rem
1rem
em
1em
pt
12pt
pc
1pc
in
0.1667in
cm
0.4233cm
Frequently asked questions
›Is 1rem always 16px?
By default, yes — but if you change the root font-size, all rem values scale. We let you set the root for accurate conversion.
›rem vs em?
rem is relative to root font-size; em is relative to the parent's font-size. rem is more predictable for layout.
›Why use rem over px?
rem respects user font-size preferences (for accessibility) and scales the whole layout consistently.
›Is the converter free?
Yes — fully free, no signup.