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Professional CSS Unit Converter with Batch Processing
A powerful tool for converting between pixels (px) and rem units in CSS. Features batch conversion, conversion history, and keyboard shortcuts for efficient workflow.
The PX to REM Converter tool helps you convert between pixels and rem units for responsive web design. REM units are relative to the root element's font size, making them ideal for scalable, accessible designs.
What is REM? REM (Root EM) is a CSS unit that is relative to the font size of the root element (html). If the root font size is 16px, then 1rem = 16px, 2rem = 32px, and so on. This makes REM ideal for creating scalable, accessible layouts.
The main converter allows you to convert individual values between pixels and rem units.
Switch between PX to REM and REM to PX modes using the toggle button. The converter adapts to show the active input field with enhanced visibility.
By default, conversion happens automatically as you type. Disable auto-convert to manually trigger conversion with the Convert button or Ctrl+Enter.
rem = px / baseFontSize
Example: 32px / 16px = 2rem
px = rem × baseFontSize
Example: 2rem × 16px = 32px
The batch conversion feature allows you to convert multiple values at once. This is especially useful when migrating existing CSS from pixels to rem units.
Enter values on separate lines. The tool automatically detects the unit (px or rem) and converts accordingly:
16px 1.5rem 24px 2rem 32px 0.75remTip: Batch conversion is perfect for converting entire CSS files. Copy your pixel values, paste them here, convert, then copy the results back to your stylesheet.
The tool automatically saves your recent conversions, storing up to 20 entries. This feature allows you to revisit and reuse previous conversions.
Switch to the "History" tab to see all your recent conversions with timestamps and base font size settings.
Click any history item to restore those values and settings. The converter will revert to the base font size used for that conversion.
Export your conversion history as a JSON file for documentation or to share with team members.
Remove all history entries with the Clear button. This action cannot be undone.
The base font size is the foundation for all REM calculations. By default, it's set to 16px (the browser default), but you can customize it to match your project's root font size.
Browser default, most common for web projects
Easy calculation: 1rem = 10px
Often used for larger, readable typography
Alternative for accessibility-focused designs
Important: Match the base font size in this tool to the root font size defined in your CSS (usually on the `html` element). This ensures accurate conversions that work with your design system.
Speed up your workflow with these keyboard shortcuts:
| Shortcut | Action |
|---|---|
| Ctrl + Enter | Convert the current value |
| Ctrl + C | Copy the converted result |
| Ctrl + R | Reset both input fields |
Note: On Mac, use Cmd instead of Ctrl.
Common pixel to rem conversions at the default 16px base font size. Click any value to use it in the converter.
Convert legacy pixel-based CSS to modern REM units for better scalability and accessibility. Use batch conversion to process entire stylesheets.
REM units scale naturally with user preferences and browser settings, making your designs more accessible across different devices and font size settings.
Establish consistent spacing and sizing in your design system by converting design specs (often in pixels) to REM units.
REM units respect the user's root font size preferences, ensuring your designs remain usable for users who need larger text.
Build reusable components with relative sizing. Changes to the root font size will propagate throughout your components automatically.
Convert design measurements to developer-friendly REM values, ensuring accurate implementation in code.