| Zero | For 0, unit is optional |
| Em of float | Relative to the font size |
| Ex of float | Relative to the x-height |
| Px of float | Relative to the viewing device |
| Gd of float | Relative to the grid |
| Rem of float | Relative to the font size of the root |
| Vw of float | Relative to the viewport's width |
| Vh of float | Relative to the viewport's height |
| Vm of float | Relative to the smallest of the viewport's width or height |
| Ch of float | Relative to the width of a char '0' |
| Mm of float | in Milimeter |
| Cm of float | in Centimeter |
| In of float | in Inch |
| Pt of float | in Points (72pt = 1in) |
| Pc of float | in Picas (1pc = 12pt) |