About REM to VW/VH Conversion
This tool converts REM units (relative to root font size) to viewport units (vw/vh) that are relative to the browser viewport size. 1vw = 1% of viewport width, 1vh = 1% of viewport height.
How to Use This Tool
- Enter the REM value you want to convert
- Select whether to convert to vw (viewport width) or vh (viewport height)
- Specify your root font size in pixels (default is 16px)
- Enter the viewport size in pixels (defaults shown based on selection)
- Click "Convert to VW/VH" to get the equivalent value
- Copy the result and use it in your CSS
The Conversion Formula
The formula to convert REM to viewport units is:
vw = (rem × root-font-size) / viewport-width × 100vw
vh = (rem × root-font-size) / viewport-height × 100vh
For example, to convert 2rem to vw when root is 16px and viewport is 1920px:
(2 × 16) / 1920 × 100vw = 1.66667vw
Why Convert REM to Viewport Units?
- True Viewport Scaling: Create elements that scale perfectly with viewport size
- Fluid Typography: Implement responsive font sizes that adapt to screen dimensions
- Full-screen Layouts: Design elements that maintain proportions across devices
- Precise Control: Achieve exact scaling relationships in responsive designs
Key Differences Between REM and Viewport Units
- REM is relative to the root element's font size
- VW/VH are relative to the viewport dimensions
- REM provides consistent sizing based on typography
- VW/VH provide fluid scaling based on screen size
- REM is often better for accessibility, VW/VH for responsive layouts
Best Practices
- Use REM for typography and spacing
- Use VW/VH for elements that should scale with viewport
- Combine with min/max values to prevent extreme scaling
- Test on various device sizes to ensure proper behavior
- Consider accessibility when using viewport units for text