PX to REM Converter
Convert pixels (px) to rem units for responsive and accessible CSS with configurable base font size
Base Font Size
Default browser size is 16px
Converter
Common Values (at 16px base)
Conversion Formula
Recommended Settings
Why Use REM?
- •Respects user's browser font size preferences for better accessibility
- •Easier to maintain consistent spacing and typography across your site
- •Scales proportionally when users zoom or adjust font settings
- •Prevents layout breaking when users increase default font size
When to Use PX vs REM
- •Use REM for font sizes, padding, margin, and most layout dimensions
- •Use PX for borders, shadows, and fine details that shouldn't scale
- •Use PX for specific measurements that must remain constant
- •Standard base is 16px (browser default) - avoid changing unless necessary
Most Popular
Most developers use 16px base font size with 3 decimal precision for REM values
When to Use This Tool
Convert pixel-based designs to rem units for truly responsive layouts that adapt to user preferences. REM units scale proportionally with the root font size, making it easier to create layouts that work across different screen sizes and user settings.
Ensure your typography respects users' browser font size preferences. When users increase their default font size for better readability, rem-based layouts scale accordingly, while px-based layouts remain fixed and potentially unreadable.
Convert design specifications from pixels to rem units for design system implementation. Use consistent rem-based spacing scales (0.25rem, 0.5rem, 1rem, 1.5rem, 2rem) for maintainable and scalable component libraries.
Create flexible layouts that scale smoothly across devices. Combine rem units with responsive techniques like media queries and fluid typography for layouts that adapt gracefully to different viewport sizes and user preferences.
How It Works
Set the base font size (default is 16px, matching browser defaults)
Enter a value in pixels (or rem if using reverse mode)
The tool automatically calculates and displays the equivalent rem (or px) value
Adjust decimal precision (2-4 places) for your preferred accuracy
Click common values for quick conversions of standard sizes
Copy the converted value to use in your CSS
Use swap direction to convert from rem to px instead
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Files never leave your device. All processing happens locally in your browser.
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Frequently Asked Questions
Why should I use REM instead of PX?
REM units respect user font size preferences, making your site more accessible. When users increase their browser's default font size (common for visually impaired users), rem-based layouts scale accordingly. PX units ignore these preferences, potentially making content unreadable for some users.
What is the standard base font size?
The standard base font size is 16px - this is the default in all major browsers. Unless you have a specific reason to change it, stick with 16px as your base. Changing the base font size can affect how your site appears relative to other websites.
What's the difference between REM and EM?
REM is relative to the root (html) font size, while EM is relative to the parent element's font size. REM is more predictable because it's always calculated from the same base value. EM can compound when nesting elements, making calculations more complex.
Do all browsers support REM units?
Yes! REM units are supported in all modern browsers including Chrome, Firefox, Safari, Edge, and even IE9+. Browser support is excellent with over 99% global coverage, making it safe to use in production.
Should I convert ALL pixels to rem?
No. Use REM for typography, spacing (padding/margin), and flexible layout dimensions. Use PX for borders, box-shadows, and fine details that should remain constant regardless of font size. For example, a 1px border should stay 1px, not scale with font size.
How does this affect responsive design?
REM units work excellently with responsive design. Combined with media queries, they allow you to adjust the base font size at different breakpoints, which automatically scales all rem-based values. This creates truly fluid, scalable layouts that adapt to both viewport size and user preferences.