rem to px Converter
Convert rem to px or px to rem with custom root font size. Enter 1.25rem, 3rem, or any value and get instant results in your browser - no upload, no account.
Runs locally in your browser. Your input is not uploaded to DevToolMate servers.
Developer Quick Tips
- Convert specific values like 1.25rem to px, 3rem to px, or 0.5rem to px by entering the value and reading both unit results instantly.
- Set custom root font size (default 16px) to match your design system - change to 14px, 18px, or any base and all conversions recalculate immediately.
- Enter px values like 24px or 16px to convert to rem using your configured root font size - bidirectional math runs entirely in your browser.
- Copy px or rem results directly into CSS or design specs - all conversion math stays local on your device, no server upload.
- Validate input format instantly - tool rejects malformed values and shows clear error messages for px and rem syntax.
Frequently asked questions
How do I convert rem to px?
Enter a rem value like 1.5rem, 1.25rem, or 0.5rem. The tool instantly calculates px using your root font size (default 16px). Example: 1.5rem with 16px root = 24px. Adjust the root font size to match your design system and conversions update immediately.
How do I convert px to rem?
Enter a px value like 24px, 16px, or 20px. The tool instantly calculates rem using your root font size. Example: 24px with 16px root = 1.5rem. Change the root font size if your project uses 14px, 18px, or another base.
Can I convert specific values like 1.25 rem to px or 0.5 rem to px?
Yes. Enter any rem value with decimals (1.25rem, 0.5rem, 2.75rem, 3rem) and get exact px equivalents. Similarly, enter any px value and get rem results. The tool handles fractional values for precise spacing and typography calculations.
What is the default root font size and can I change it?
Default is 16px, the browser standard. You can set any custom root font size (14px, 18px, 20px, etc.) to match your design system. All conversions recalculate instantly based on your root setting.
How do I use this converter for design tokens?
Set your root font size to match your design system base (e.g., 16px or 14px). Enter each token value in rem or px and verify the conversion. This ensures spacing scales and typography tokens are consistent across your design system.
Does the converter upload my input to a server?
No. The converter runs entirely in your browser. Your input is never uploaded to DevToolMate servers - all conversion math stays on your device for the current session.
Is the converter free and do I need an account?
Yes, completely free with no account required. Processing happens locally in your browser. No login, no signup, no limits.
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- Aspect Ratio Calculator: Free aspect ratio calculator for CSS aspect-ratio property. Enter 16:9 or pixel dimensions to get simplified ratios, CSS declarations, and responsive sizing, all in your browser, no upload.