| Name | Description |
| px (pixels) | |
| mm (millimeters) | 3.8px |
| cm (centimeters) | 38px |
| in (inches) | 96px |
…
| pt (points) | 4/3px |
| pc (picas) | 16px |
| ex | Relative to the x-height of the current font |
| ch | Relative to width of the «0» (zero) |
| % | 1% of parent width.
|
| em | Relative to the font-size of the element (2em means 2 times the size of the current font) |
| rem | Relative to font-size of the root element (html) |
| vw | Relative to 1% of the width of the viewport |
| vh | Relative to 1% of the height of the viewport |
| vmin | Relative to 1% of viewport’s smaller dimension
|
| vmax | Relative to 1% of viewport’s larger dimension |
| fr (fraction) | Relative to 1% of viewport’s larger dimension |
Support
| Length Unit |  |
 |
 |
 |
 |
| em, ex, %, px, cm, mm, in, pt, pc | 1.0
(12/11/2008) |
3.0
(8/13/1996) |
1.0
(10/27/2004) |
1.0
(6/23/2003) |
3.5
(1998) |
| ch | 27.0
(5/21/2013) |
9.0
(3/14/2011) |
1.0
(10/27/2004) |
7.0
(10/22/2013) |
20.0
(3/4/2014) |
| rem | 4.0
(1/25/2010) |
9.0
(3/14/2011) |
3.6
(8/7/2009) |
4.1
(6/7/2010) |
11.60
(12/6/2011) |
| vh, vw | 20.0
(5/1/2012) |
9.0
(3/14/2011) |
19.0
(10/9/2012) |
6.0
(7/25/2012) |
20.0
(3/4/2014) |
| vmin | 20.0
(5/1/2012) |
9.0 (vm)
(3/14/2011) |
19.0
(10/9/2012) |
6.0
(7/25/2012) |
20.0
(3/4/2014) |
| vmax | 26.0
(3/26/2013) |
Not supported | 19.0
(10/9/2012) |
7.0
(10/22/2013) |
20.0
(3/4/2014) |
version (release date)