This is a summary of UsingKeywords, UsingPixels, UsingPoints, UsingEms, and UsingPercentages.
Also see: AvoidingHacks
| Method | Advantages | Disadvantages |
| Keywords | Not influenced by nearby font sizes so easier to manage | Limited choices, only 7 sizes |
| Pixels | Consistent across browsers | Fixed size disregards user needs. Physical size is smaller as display resolution is increased. IE/Win buggy, see ForceFontSize. |
| Points | Good for print style sheets (but with possible user accessibility problems) | Inconsistent (e.g. between PC and Mac) on screen; depends upon system DPI, which is rarely set close to reality on a PC. |
| Ems | Relative sizing | Cascade bugs in IE (fixes available) |
| Percents | Relative Sizing | Cascade math requires a little more thought than non-relative sizes |
| Ems w/ Percent Base | Relative sizing / Good browser suport / Centralised control in the CSS file | Easily overridden by user stylesheet |
| Method | Code |
| Keywords | p { font-size: x-large; } |
| Pixels | p { font-size: 18px; } |
| Points | p { font-size: 12pt; } |
| Ems | p { font-size: 1.2em; } |
| Percents | p { font-size: 85%; } |
| Ems w/ Percent Base | body { font-size: 80% } p { font-size: 1em; } |