The <dimension> CSS data type represents a <number> with a unit attached to it, for example 10px.

CSS uses dimensions to specify distances (<length>), durations (<time>), frequencies (<frequency>), resolutions (<resolution>), and other quantities.


The syntax of <dimension> is a <number> immediately followed by a unit which is an identifier. Unit identifiers are case insensitive.


Valid dimensions

12px      12 pixels
1rem      1 rem
1.2pt     1.2 points
2200ms    2200 milliseconds
5s        5 seconds
200hz     200 Hertz
200Hz     200 Hertz (values are case insensitive)

Invalid dimensions

12 px       The unit must come immediately after the number.
12"px"      Units are identifiers and therefore unquoted.
3sec        The seconds unit is abbreviated "s" not "sec".


Specification Status Comment
CSS Values and Units Module Level 4
The definition of '<dimension>' in that specification.
Editor's Draft Adds cap, ic, lh, rlh, vi, vb
CSS Values and Units Module Level 3
The definition of '<dimension>' in that specification.
Candidate Recommendation Adds ch, rem, vw, vw, vmin, vmax, Q
CSS Level 2 (Revision 1)
The definition of '<dimension>' in that specification.
Recommendation Defined under Numbers and Length
CSS Level 1
The definition of '<dimension>' in that specification.
Recommendation Initial definition under "length units"

Browser compatibility

Update compatibility data on GitHub
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
<dimension>Chrome Full support 1Edge Full support 12Firefox Full support 1IE Full support 5Opera Full support 3.5Safari Full support 1WebView Android Full support ≤37Chrome Android Full support 18Firefox Android Full support 4Opera Android Full support 10.1Safari iOS Full support 1Samsung Internet Android Full support 1.0


Full support  
Full support

See also