Px to REM / EM Converter

Convert pixel values to REM and EM units for responsive CSS. Batch convert multiple values.

Settings

1rem = 16px

Quick Convert

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Common Size Reference

PX REM EM %

Batch Convert (px values, one per line)

PX Input
REM Output

          

        

      

    

  

  







  
About the Px to REM / EM Converter

  

    The Px to REM Converter translates pixel values into relative CSS units (REM, EM and %) using a configurable base font size, making it easy to write accessible, scalable stylesheets. It supports quick single-value conversion, a common-sizes reference table and a batch mode for converting entire lists of pixel values at once. Everything runs instantly in the browser  -  no server needed.
  

  
Common use cases

  




  
Frequently Asked Questions

  


    

      How does the px to REM conversion work?
      
The conversion is a simple division: rem = px / base font size. By default the base is 16px, which is the browser default for the root <html> element, so 32px becomes 2rem. If your project sets a different root font size (say 10px for easier math), you can change the base in the Settings panel and every value in the reference table and batch converter updates instantly.

    


    

      Why should I use REM instead of pixels in CSS?
      
REM units scale relative to the root font size, which means your entire layout respects a user's browser accessibility settings when they increase the default text size. Pixel values are absolute and ignore these preferences, potentially breaking accessibility for low-vision users. Using REM also makes global scaling trivial  -  changing the root font size once adjusts your entire type and spacing scale proportionally.

    


    

      What is the difference between REM and EM?
      
REM (root em) is always relative to the font size of the root <html> element, making it consistent throughout the document regardless of nesting. EM is relative to the font size of the current element's parent, which means nested elements can compound unpredictably (e.g., an em-sized child inside an em-sized parent doubles the scaling). REM is generally preferred for spacing and layout, while EM can be useful for component-level scaling that should adapt to its local context.

    


    

      Is my data safe when using the batch converter?
      
Yes. All conversions  -  including the batch mode  -  happen entirely in your browser using JavaScript. No pixel values or results are sent to any server, stored in a database or logged anywhere. You can safely paste sensitive design tokens or internal spacing values without any privacy concern.

    


    

      How does this compare to converting px manually or using a preprocessor?
      
Manual division is error-prone at scale  -  a single wrong calculation can break your spacing system across many components. Sass or Less functions like px-to-rem() work at build time but require a build pipeline setup. This tool gives you instant, zero-setup conversion without any dependencies, making it ideal for quick checks, design handoff reviews and one-off conversions outside of a build environment.