DevConvertor

PX ↔ REM Converter

Convert between pixels and rem, with a configurable root font size (16px by default, with common presets). Edit either field and the other updates to match — useful for translating a design's pixel values into rem-based CSS.

Root font size:

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Features

  • Configurable root font size, with common presets
  • Edit either field — the other updates to match
  • Accurate decimal handling

How to use

  1. Set the root font size (defaults to 16px).
  2. Enter a value in either the px or rem field.

FAQ

Why does the root font size matter?
rem is always relative to the root (<html>) element's font size — 16px by default in most browsers, but a site can change it. Converting correctly requires knowing that value, which is why it's configurable here rather than hardcoded.
Example?
At a 16px root size, 16px = 1rem and 32px = 2rem. Change the root size and the conversion updates accordingly.