Skip to content
A Polyfill for CSS3 calc()
JavaScript HTML CSS
Branch: master
Clone or download
rodebert Add single distribution directory - fixes #24
Signed-off-by: Robert Weber <>
Latest commit c6611a3 Jan 25, 2016
Type Name Latest commit message Commit time
Failed to load latest commit information.
dist Add single distribution directory - fixes #24 Jan 25, 2016
.editorconfig editor config Feb 9, 2015
Gruntfile.js Add single distribution directory - fixes #24 Jan 25, 2016
LICENSE Updated readme Jul 30, 2015

A Polyfill for CSS3 calc()

This is a javascript poly fill for the CSS3 calc-function.

Inspired by:


Simply drop the link like this after you included your CSS:

<script type="text/javascript" src="path/to/calc.js"></script>

A test for the support if calc() is integrated based on the Modernizr test

Tested on Internet Explorer 8 and Android 4.0.3


  • support for document.querySelectorAll
  • for media queries window.matchMedia



This polyfill does not take specificity into account when applying styles for calc().

For example if you have to rules:

.element  div {
	width: calc(50% - 230px);

div {
	width: calc(50% - 100px);

The first rule would apply for the <div /> element because of higher specificity. The CSS is parsed from top to bottom and therefore the polyfill would apply the styles of the second rule. Just keep that in mind.


This polyfill also does not detect any resetting of calc():

.element  div {
	width: calc(50% - 230px);

div {
	width: 50%;

The polyfill will apply the rules from the first as it is not detecting the resetting of the width in the second.

Inline Styles

Support for polyfilling inline styles is integrated. However right now there seems no way to get the unparsed contents of a <style /> element in IE8 and therefore the polyfill will not work there. IF you find a way to do this let me now or make a PR.


There is currently no support for libs like respond.js and it is not planned to add support. However the polyfill uses window.matchMedia to test for media queries. If you wish to add support for media queries for IE8 include a polyfill before the calc-polyfill.

To Do

  • more Android testing
  • consider imported CSS files wie @import
You can’t perform that action at this time.