Best Free Online Developer Tools to Use in 2026
A practical, opinionated list of the best free online developer tools worth using in 2026, organized by category so you can find what you need fast.
Aug 08, 2026
REM to PX Converter
Convert REM/EM units to PX based on configurable root font size with live preview and batch conversion.
REM / EM to PX Converter
px
| REM | PX | Preview |
|---|
- Set root font size — Enter your base font size (default 16px).
- Enter values — Type or paste REM/EM values, one per line or comma-separated.
- Toggle units — Check "Use EM units" to convert EM instead of REM.
- Copy result — Click the Copy button or use the table preview to see all values.
What is the difference between REM and EM?
REM (Root EM) is relative to the root element's font size (usually 16px). EM is relative to the parent element's font size. This tool uses the root font size for both when "Use EM units" is unchecked.
What is the default root font size?
Most browsers default to 16px, but you can adjust it to match your design system's base font size (e.g., 14px, 18px, 20px).
What is the formula for REM to PX?
PX = REM × Root Font Size. For example, 2rem with a 16px base = 32px. EM follows the same formula when using the root font size setting.
Last updated: 17 Aug 2026
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