How Is Font Size Measured?
- The most common way fonts are measured are by font length. A font length can be relative or absolute. This can be an integer or decimal number followed by one of the supported font length types.
Relative font length types are: "em" for ems, "ex" for x-height and "px" for pixels. An example would be "font-size: 1.2 em" for 1.2 times the inherited font size of the HTML element. Relative font lengths like "em" will inherit the font sizes of parent HTML elements in relation to the em value.
Pixel font sizes are not relative to their parent elements, but they are relative to the display resolution of the computer monitor. - Absolute font length types are "pt" for points, "mm" for millimeters, "cm" for centimeters, "in" for inches and "pc" for picas. An example would be "font-size: 12 pt" for a twelve-point font size. Absolute font sizes are based on physical sizes but can still vary between font families.
- Absolute font sizes are: "xx-small," "x-small," "small," "medium," "large," "x-large" and "xx-large." These are all preset sizes. "Medium" is the default size of standard font size elements. Making relative font size changes will either ascend or descend along this font size list.
- Relative font sizes are "larger" or "smaller." Relative font sizes will increase or decrease the font size in relation to the default font size and inherited font sizes. For example, if the inherited or default font size of an element is a medium size and the font size of that element is set to "larger," then the calculated font size will result in a "large" font size.
- The percentage font size is simply a percentage of the element's inherited or default font size. For example, a "font-size: 90%" would result in the element rendering at 90 percent of the size it would have without any font size explicitly set.