Why does this assume 16px?

16px is the default root font size in every major browser unless a site explicitly overrides it on the element. Adjust manually if your project uses a different base size.

Rem to PX Converter

Convert rem units to pixel values, live as you type, based on the standard 16px root font size.

100% private, runs in your browser

Rem

Pixels (px)

Assumes the default 16px root font size. Type in either field — the other updates live.

Need the opposite? Use PX to Rem Converter

What is Rem to PX Converter?

Convert a rem value back to pixels, assuming the standard 16px browser default root font size — useful when translating a CSS design spec written in rem into exact pixel measurements for design tools or documentation.

FAQ

16px is the default root font size in every major browser unless a site explicitly overrides it on the <html> element. Adjust manually if your project uses a different base size.

This converter is specifically for rem (relative to the root font size). em is relative to the parent element's font size instead, which this tool doesn't account for.