CSS Unit Converter
Convert between PX, REM, and EM units with a configurable base font size.
Frequently Asked Questions
What is the difference between REM and EM?
rem (Root EM) is relative to the root element (usually the <html> element) font size. em is relative to the font size of its nearest parent element.
Why use REM instead of pixels?
Using rem units is crucial for accessibility. If a user changes their browser's default font size, your entire layout scales proportionally — something static pixel units can't do.