CSS Tools

PX to REM Converter

Convert pixel values to rem based on your root font size (default 16px). Includes batch conversion, rounding, and copy-ready output.

Fast No tracking Batch convert

One value per line (numbers only).

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Why use rem instead of px?

rem scales with the user’s base font-size (accessibility settings, zoom, OS preferences). That usually results in more resilient typography and spacing across devices and user settings.

  • Improves accessibility for users who increase text size
  • Makes design systems easier to scale consistently
  • Pairs well with modern responsive layouts

Quick examples

Base = 16px
16px  →  1rem
24px  →  1.5rem
32px  →  2rem

Formula: rem = px / base

FAQ

What root font-size should I use?
Most sites use 16px (browser default). If your CSS sets html { font-size: 62.5%; }, then your “base” is typically 10px.
Does rem affect Core Web Vitals?
Indirectly: rem helps you build predictable layouts and typography. The real CWV gains still come from controlling layout shifts (CLS), responsive media sizing, and performance optimizations.
Can I convert a whole CSS snippet?
This tool converts numeric values line-by-line. If you want a “paste CSS / convert automatically” tool, that’s a separate utility (and a great next addition).
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Need help fixing layout issues or improving CWV?

If your site has inconsistent spacing, unexpected shifts, or slow pages, I can audit and stabilize it (especially for WordPress + page builders).

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