PX to REM Converter

Convert pixels (px) to rem and rem to pixels with a custom base font size. Free CSS unit converter.

rem

px

1rem equals 16px at the current base size. Change the base size above.

What is a PX to REM Converter?

A px to rem converter is a free online tool that converts pixel values to rem units and back, using a configurable base font size. It helps developers build responsive, accessible layouts.

How to use

  • Choose the base font size (default 16px)
  • Type a value in either field — the conversion happens instantly in the other
  • Copy the resulting value into your CSS

Key features

  • Instant two-way conversion
  • Configurable root font size
  • Works with decimal values
  • Free and runs entirely in your browser

Frequently Asked Questions

What is rem?+
rem is a CSS unit relative to the root element’s font size (usually html). Unlike em, it isn’t affected by parent font sizes.
What is the base font size?+
The default base is 16px — the browser default — and you can switch to 14, 15, 17, 18 or 20px.
How do I convert px to rem?+
Divide the pixel value by the base font size: 16px ÷ 16 = 1rem. The tool does this instantly.
Why use rem instead of px?+
rem scales with the root font size, which makes responsive layouts easier and respects the user’s browser font-size setting.

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PX to REM Converter — free online px to rem, rem to px, px rem converter, css unit converter, root font size, responsive typography, pixel to rem, rem calculator. No signup required. Works in your browser.