H1_PX to REM Converter - CSS Units | MultiTool

How it works

Enter your root font size (16px by default), then convert either direction: px to rem or rem to px, with a quick table of the most common font sizes.

The px vs rem decision, settled

rem is relative to the root font-size (16px by default), px is absolute. That single difference drives the whole modern CSS strategy:

• Accessibility: users who raise their browser's default text size get larger text only if you used rem. Hard-coded px ignores their choice — the #1 reason accessibility audits flag stylesheets.
• The pattern professionals use: rem for everything that reads (font sizes, line-height, margins around text), px for things that must stay fixed (1px borders, shadows, hairlines).
• The math: rem = px ÷ 16. The classic scale — 0.75 (12px), 0.875 (14px), 1 (16px), 1.125 (18px), 1.25 (20px), 1.5 (24px), 2 (32px) — covers 95% of real designs.
• Media queries too: rem-based breakpoints respect user zoom consistently across browsers.

Your privacy

Everything runs entirely in your browser. Nothing you type is ever sent to any server or stored.