The cap height (short for capital height) is at the top level of square capital letters, such as H.

The cap height is one of the main guidelines for Latin-script typefaces. It is usually lower than the ascender height in typefaces meant to be used at small size. This is also the case for sans serif styles to show a difference between l (lowercase L) and I (uppercase i). In many display styles, the ascenders are the same as the cap height to save some vertical space.