What is the difference between PX, REM, and EM in CSS?

PX is a static fixed pixel value. REM is relative to the root html font-size (default 16px). EM is relative to the parent element font-size.

Why do developers prefer REM over PX for typography?

REM units respect user font scaling settings configured in browser accessibility options, ensuring accessible and responsive web design.

Scenic Interactive Tool

Convert static pixel (px) sizes to relative rem / em CSS units instantly. Customize root font size (default 16px) and copy quick cheat sheet values.

Root <html> Font Size (Base PX): (Default browser base size is 16px)

Pixels (PX):

REM / EM:

Pixels (px)	REM Equivalent	Action

REM = Target Pixels / Root Font Size. For example, 24px / 16px = 1.5rem.

REM always calculates relative to the root <html> element, whereas EM calculates relative to the font-size of its immediate parent container.