Firefox Browser Add-ons
  • Extensions
  • Themes
    • for Firefox
    • Dictionaries & Language Packs
    • Other Browser Sites
    • Add-ons for Android
Log in
Preview of UnitShift — CSS Unit Converter

UnitShift — CSS Unit Converter by Dixie Raiz Pacheco

Convert px, rem, and em units with one click inside Firefox DevTools. Select any element and apply conversions live.

0 (0 reviews)0 (0 reviews)
Download Firefox and get the extension
Download file

Extension Metadata

Screenshots
About this extension
UnitShift is a DevTools sidebar that converts CSS units (px, rem, em) with one click — right where you're already inspecting elements.

The problem: AI-generated code and Figma-to-code workflows output everything in px. Converting to rem or em means mental math, calculators, or separate tools outside your workflow. Letter-spacing is especially tricky — its em value is relative to the element's own font-size, not the parent's.

How it works:

Open DevTools → Inspector panel
Select any element
UnitShift reads all computed CSS properties with unit values
Click a convert button to switch between px, rem, and em
The value is applied as an inline style instantly — same as editing in the Rules pane
Features:

Context-aware em conversion — knows that letter-spacing, word-spacing, and line-height use the element's own font-size, while padding, margin, and other box model properties use the parent's
Properties grouped by category: Typography, Spacing, Sizing, Position, Border
Bulk "Convert All" to switch every value at once
Configurable base font-size (default 16px)
Zero configuration needed — works out of the box
No permissions beyond DevTools access
Pure HTML/CSS/JS, no frameworks, no external requests
Who it's for: Front-end developers who work in DevTools daily, build from Figma designs, and need responsive, accessible CSS.

Built by Dixie Raiz Pacheco — dixieraizpacheco.com
Rated 0 by 0 reviewers
Log in to rate this extension
There are no ratings yet

Star rating saved

5
0
4
0
3
0
2
0
1
0
No reviews yet
Permissions and data

Required permissions:

  • Extend developer tools to access your data in open tabs

Data collection:

  • The developer says this extension doesn't require data collection.
Learn more
More information
Add-on Links
  • Homepage
  • Support site
  • Support Email
Version
1.0.0
Size
667.81 KB
Last updated
17 days ago (Feb 11, 2026)
Related Categories
  • Web Development
License
MIT License
Version History
  • See all versions
Add to collection
Report this add-on
Go to Mozilla's homepage

Add-ons

  • About
  • Firefox Add-ons Blog
  • Extension Workshop
  • Developer Hub
  • Developer Policies
  • Community Blog
  • Forum
  • Report a bug
  • Review Guide

Browsers

  • Desktop
  • Mobile
  • Enterprise

Products

  • Browsers
  • VPN
  • Relay
  • Monitor
  • Pocket
  • Bluesky (@firefox.com)
  • Instagram (Firefox)
  • YouTube (firefoxchannel)
  • Privacy
  • Cookies
  • Legal

Except where otherwise noted, content on this site is licensed under the Creative Commons Attribution Share-Alike License v3.0 or any later version.