PX to REM Converter
Convert pixel values to rem, with a configurable root font size - the common default is 16px, but this tool never assumes that silently.
Enter a pixel value and your root font size - this tool divides correctly and shows the exact formula used.
For the reverse conversion, see the REM to PX Converter - or use the full CSS Unit Converter for more unit types at once.
The px to rem Formula
rem value = pixels ÷ root font size. With the standard 16px root, 24px becomes 1.5rem - but if your project sets a different root size (common for accessibility or design-system reasons), the result changes accordingly.
Why Use This Tool?
Doing this division by hand repeatedly while converting a whole stylesheet is tedious and easy to mistype - this tool does the arithmetic instantly and shows the formula so you can verify it.
How to Use It
- Enter your pixel value.
- Set your root font size (16px by default - change it if your project uses a different base).
- Read the resulting rem value.
Common Errors
The most common mistake is assuming 16px when a project has actually set a different root size (e.g. many design systems use 62.5% on html, making 1rem = 10px) - always confirm your project's actual root size rather than assuming.