PX to REM Converter — Responsive Font Size & CSS Unit Tool
Convert pixel values to rem and em CSS units instantly. Set your root and parent font sizes, enter a single px value for a live result, or paste a list of values to convert in bulk. Includes a common sizes reference cheat sheet.
How to Use PX to REM Converter — Responsive Font Size & CSS Unit Tool
How to Use the px to rem/em Converter
Step 1: Set Base Font Sizes
Configure the two base sizes used for conversion:
- Root Font Size — the
font-sizeon the<html>element. The browser default is 16px. Changing this affects all rem calculations. - Parent Font Size — the inherited font size of the element you are targeting. This determines em values and changes per component.
Step 2: Convert a Single Value
Enter any pixel value in the Single Value input. The rem and em results update instantly. Click either result chip to copy it directly to your clipboard.
Step 3: Bulk Convert Multiple Values
Paste or type multiple pixel values in the Bulk Converter textarea — separate them by commas, spaces, or newlines. The px suffix is optional. Click a preset to load a common scale:
- Spacing Scale — design system spacing tokens (4–64px)
- Type Scale — typography sizes (10–64px)
- Tailwind — Tailwind CSS spacing scale
Click Copy as TSV to copy the results as a tab-separated table ready to paste into a spreadsheet.
Step 4: Use the Reference Table
The Common Sizes Reference table shows pre-calculated conversions for the most frequently used pixel values. The row matching your current single value is highlighted in blue. Click Copy as TSV to export the entire table.
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