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Pixel to REM Converter

Convert pixel values to REM and EM units based on a custom base font size, and convert back. Free, instant, runs entirely in your browser.

💻 Developer Tools Free Browser-based
Tool
1rem
REM value
1em
EM value
16px
PX (from REM)
Common conversions (base 16px)
PXREMEM

PX vs REM vs EM

px (pixels) are absolute units — they always render at the same physical size regardless of the user's font preferences. rem (root em) is relative to the root element's font size (typically the <html> element), defaulting to 16px in most browsers. em is relative to the parent element's font size, which can compound in nested elements. For most responsive designs, rem is preferred over em because it always stays relative to a single predictable base.

Common Conversions at Base 16px

PXREMEM
12px0.75rem0.75em
14px0.875rem0.875em
16px1rem1em
18px1.125rem1.125em
24px1.5rem1.5em
32px2rem2em
48px3rem3em

Tips

If your project uses a non-standard base font size (e.g. 62.5% trick sets it to 10px), change the base field to match. All conversions update instantly. Using rem for font sizes and spacing makes your layout scale correctly when users change their browser's default font size in accessibility settings.

Frequently Asked Questions