CSS Unit Converter
Convert between px, rem, em, and percentage instantly.
Customize base values for accurate conversions.
1rem16px / 16px = 1.0000rem
About CSS Units
PX (Pixels) - Absolute units. 1px is always 1 pixel on the screen.
REM (Root EM) - Relative to the root element's font size. Default is 16px in most browsers.
EM - Relative to the parent element's font size. Useful for component-level scaling.
% (Percentage) - Relative to the parent container's width (for width values) or other properties.
When to Use Each Unit
Use REM for:
- Font sizes
- Spacing (margin, padding)
- Accessibility-friendly layouts
Use EM for:
- Component-specific spacing
- Button padding relative to text
- Icon sizes relative to text
Use PX for:
- Borders
- Box shadows
- Fine-tuned adjustments
Use % for:
- Responsive widths
- Fluid layouts
- Grid column sizes
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