CSS Unit Converter
Type a value into any unit and the others update live. Default root font-size is 16px; adjust it if your project uses a different base.
Common sizes
| px | rem | em | pt | % |
|---|
How to Use
Enter into px, rem, em, pt, or % — the rest update automatically.
Set the root font-size (drives rem) and parent font-size (drives em and %). Both default to 16px.
Use the copy buttons next to each unit. A common-size table (8/12/14/16/18/20/24px) is also shown.
FAQ
rem vs em?
rem is relative to the root html element's font size (typically 16px). em is relative to the current element's parent font size. rem is absolute-ish; em compounds.
Why is the root size 16px?
Most browsers (Chrome, Safari, Firefox) ship with html font-size: 16px by default. Without user overrides, 1rem = 16px is the standard.
Are % and em the same?
For font-size, yes — 100% = 1em. But % means different things for width/height/etc. (parent's value of that property).
When is pt useful?
pt is a print unit (1pt ≈ 1.333px). Rare on the web but handy for PDF and print previews.
Is anything sent to a server?
No. All conversion happens in your browser; values never leave the page.
