Lab — Dev Tools

PX ⇄ REM Converter

PX ⇄ REM Converter is a free online tool that converts pixel values to rem units and back at any root font size — type a value, get the exact conversion instantly, copy the result or a ready-to-paste CSS declaration, and check the quick reference table for common sizes. No account, nothing leaves the page.

Pixels

Rem

rem

Root font-size (base)

Press Enter in the px field to copy the rem value. Your base size is remembered on this device.

CSS snippet

Common values ·

px	rem

Click any rem value to copy it.

How it works

The formula — rem = px ÷ base and px = rem × base. At the default 16px base, 20px is 1.25rem.
Why rem — rem units scale with the reader's root font size, so a layout set in rem respects the browser's text-size setting while px stays fixed.
Rounding — results are rounded to at most 4 decimal places, with trailing zeros trimmed, so 15px at 16 is 0.9375rem and 1px is 0.0625rem.