Convert px to rem at any root font size. Batch-convert CSS and skip 1px borders. Free px to rem tool runs entirely in your browser.
rem (root em) is relative to the font size on the <html> element. With the browser default of 16px, 1rem equals 16px and 24px equals 1.5rem. Changing the base field in this tool mirrors that ratio.
Unlike px, rem respects the user’s browser font-size setting, which matters for accessibility and low-vision users. Fixed px sizes ignore those preferences.
Some codebases set html { font-size: 62.5% } so 1rem ≈ 10px for “easy math.” That trick requires resetting body font size and often breaks third-party components that assume a 16px root.
em is relative to the parent element’s font size and compounds with nesting — a nested 1.2em inside another 1.2em is not 1.2rem. rem stays tied to the root, which is why layout spacing usually uses rem.
Hairline borders are often left at 1px because sub-pixel rem borders can look inconsistent across displays. Batch mode can skip 1px values for that reason. All conversion runs in your browser.
Most browsers use 16px on html, so 1rem = 16px unless your project changes the root font size.
Setting html { font-size: 62.5% } makes 1rem = 10px when the browser default is 16px. You must reset body text size and watch for broken third-party CSS.
rem is always relative to the root. em is relative to the parent font size and stacks when nested.
1px borders and outlines often stay in px so they remain crisp; converting them to rem can produce sub-pixel rendering.
Breakpoints are frequently kept in px to match device pixels; skipping @media blocks avoids changing those thresholds.
Values are rounded to four decimal places and trailing zeros are stripped (e.g. 1.5rem).
No. Conversion runs locally in your browser.
Yes. Use Download to save converted.css after batch conversion.