PX to REM & REM to PX Converter
Convert pixel values to responsive rem units, convert entire CSS stylesheets, and customize base root font sizes with instant client-side calculation.
At a glance
PX to REM & REM to PX Converter is a free, client-side tool that converts pixels (px) to relative units (rem, em) and vice versa online. It supports 16px standard, 10px 62.5% hack, 14px compact, or any custom value. Enter pixels or rem for instantaneous two-way conversion. All processing is local: nothing is uploaded, and no account is required.
100% In-Browser CSS Unit Calculation
Stylesheets, pixel values, and typography dimensions are converted locally in browser memory. Zero code leaves your computer.
Standard CSS & Tailwind Spacing Scale Reference
Click any card to copy REMWhy Use REM Instead of Pixels in CSS?
Pixels (px) are absolute static units. When visually impaired users increase their default browser font size from 16px to 24px in operating system settings, hardcoded pixel values will not scale, breaking accessibility guidelines (WCAG 1.4.4).
REM (Root EM) scales proportionally to the <html> root font size. By using rem for margins, padding, and typography, your website honors user preferences and maintains flawless responsive harmony across mobile and desktop.
The 62.5% Root Font Size Trick
By setting html { font-size: 62.5%; } in your CSS, the default 16px base font size becomes 10px.
This allows frontend developers to easily calculate rem in their heads: 14px becomes 1.4rem, 18px becomes 1.8rem, and 24px becomes 2.4rem. This tool supports 10px and custom bases with instant recalculation.
Why Use This PX to REM & REM to PX Converter?
How to Use PX to REM & REM to PX Converter
Set Base Font Size
Set your base root font size (default is 16px).
Enter Values or Paste CSS
Enter pixel values for instant calculation or paste an entire CSS code block into the batch tab.
Copy or Download Results
Copy the converted rem measurements or grab the transformed stylesheet.
Standard Layout Spacing Conversion
Converts absolute pixel dimensions to relative, responsive REM units based on a 16px root font size.
padding: 24px 16px; margin-bottom: 32px; font-size: 18px;
padding: 1.5rem 1rem; margin-bottom: 2rem; font-size: 1.125rem;
Technical Specifications & Engine Details
| Specification | Details |
|---|---|
| Supported Formats | TEXT/CSS, TEXT/PLAIN, .CSS, .TXT → TEXT/CSS, TEXT/PLAIN, .CSS, .TXT |
| Execution Mode | 100% Client-Side In-Browser (client) |
| Browser Requirements | Modern browser with JavaScript enabled. |
| Performance Constraints | Runs client-side in browser memory. Performance and file limits are bounded by available local device RAM. |
100% Client-Side Privacy Guarantee
Your files remain strictly on your local device. Zero data is transmitted to external servers.
Frequently Asked Questions
What is the formula for converting px to rem?
Why should I use rem instead of px in CSS?
Can I convert an entire CSS stylesheet from px to rem?
Methodology
This tool runs entirely in your browser. The example above shows a representative input and the result it produces.
Last updated .