CSS Unit Converter
12 toolsConvert between px, rem, pt, and percent.
Runs in your browser — your files and text stay on your device
Convert a pixel value to rem, pt and percent for CSS. Set your root font size, since rem and percent depend on it, and copy any result. It's handy when translating a design in pixels into scalable units.
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px
16px
rem
1rem
pt
12.00pt
%
100.00%
How to use this tool
- 1Enter a pixel value, and your root font size if it's not the browser default (16px).
- 2See the equivalent rem, pt, and percentage values instantly.
- 3Click Copy next to any value to grab it.
Frequently asked questions
Why does rem depend on the root font size?
1rem always equals the <html> element's font size. If a page sets a custom root font size (common for scalable typography systems), rem values scale relative to that instead of the browser default 16px.
When should I use rem instead of px?
rem respects a user's browser font-size preference (accessibility) and scales consistently if you change the root font size — generally preferred for typography and spacing over fixed px.
Is this calculated on a server?
No — it's plain JavaScript math running in your browser.