PX to REM Converter
Keep your typography responsive by converting pixels into accessible REM units.
PX ↔ REM Converter
Root font-size (default: 16)
Batch Convert (one value per line)
PX to REM Converter – Responsive CSS Unit Calculator
The relationship between pixels and REM units is one the most important concepts in responsive web design. While px is a fixed absolute unit, rem (root em) is relative to the root element's font size. If a user increases their browser's base font size for accessibility, rem-based layouts scale accordingly. Px-based layouts stay fixed, ignoring the user's preference entirely.
By default, browsers set the root font size to 16px, meaning 1rem = 16px. Dividing any pixel value by 16 gives you the rem equivalent. This converter automates that math and supports custom base sizes for projects that use a different root font.
Why Use REM Instead of PX?
REM-based scaling enables better accessibility compliance (WCAG) and creates naturally fluid layouts that respect user-defined browser font preferences.
Custom Base Sizes
If your project sets html { font-size: 10px; } for easier math (a common trick), change the base size to 10 in this converter and get accurate results instantly.