Developer
PX to REM Converter
Convert pixels to REM and EM units using a configurable root font size.
How to use this tool
Enter a pixel value and your document root font size to calculate scalable CSS units instantly.
Related tool: Aspect Ratio Calculator →When to use the PX to REM Converter
Use it when building responsive CSS and you want sizes that scale with the user's browser font settings.
Examples
- 16 px is 1 rem with the default root font size.
- Convert a 24 px heading to 1.5 rem.
Common mistakes
- Changing the root font size and forgetting to recalculate.
- Using rem for borders and hairlines that should stay 1 px.