PX to REM Converter

Instantly convert between px, rem, and em CSS units using a configurable root font size.

px

Formula

rem = px ÷ base

px = rem × base

Enter a value to convert between px, rem and em

PX to REM Converter

The PX to REM Converter lets you instantly switch between pixel (px), root em (rem), and em values for any given root font size. Pixels are absolute units fixed to screen resolution, while rem units scale relative to the root element's font size — typically 16px in most browsers. This makes rem the preferred unit for responsive, accessible web design.

Designing with rem and em instead of px ensures your layouts and typography scale gracefully when users change their browser's default font size, which is crucial for accessibility compliance. Enter any value in px, rem, or em alongside your project's base font size and instantly see the equivalents for all three units.

How it works

rem = px ÷ base; px = rem × base; em = px ÷ parent-font-size (treated as base here). Default base is 16px (browser default).

Use cases

  • Converting design-tool pixel values to rem for CSS stylesheets
  • Ensuring accessible typography that scales with user font preferences
  • Setting spacing tokens (margin, padding, gap) in rem for responsive layouts
  • Checking that component sizes remain consistent across different base font sizes
  • Translating legacy px-based codebases to modern rem/em units

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