Percent to REM Converter

Convert Percentage (%) to REM.

1rem

What 100% equals in pixels

Default 16px

About Percent to REM Converter

The Percent to REM Converter helps developers translate percentage-based sizing into REM units. This is particularly useful when converting legacy fluid layouts to modern REM-based systems or understanding the relationship between relative font sizes. By defining what 100% represents (the reference pixel value) and the root font size, you can accurately calculate the equivalent REM value.

Formula

REM = ((Percent ÷ 100) × Reference Pixels) ÷ Root Font Size

Examples

100% of 16px (base 16) = 1rem
150% of 16px (base 16) = 1.5rem
50% of 16px (base 16) = 0.5rem

Reference

  • • Default Font Size: 100% usually equals 16px in browsers
  • • REM: Relative to root html element
  • • Common: 62.5% font-size trick makes 1rem = 10px
  • • Context matters: % depends on parent, REM on root

Frequency Asked Questions

How do I convert percent to REM?

First determine what pixel value the percentage represents (e.g., 100% of 16px = 16px). Then divide that pixel value by the root font size to get REM.

Why use REM instead of percent?

REM provides consistent sizing across the entire document regardless of nesting depth, whereas percentages compound and depend on parent elements.

What is the standard root font size?

The standard browser default is 16px, but this can be changed by user settings or CSS.