xheight

Xheight, in typography, is the height of the body of lowercase letters. It is defined by the distance from the baseline to the mean line where most lowercase letters reach, and is most visibly exemplified by the height of the letter x. The x-height is a key component of a typeface’s overall proportions and is typically contrasted with ascenders, which rise above the mean line, and descenders, which drop below the baseline. It is also related to the cap height—the height of uppercase letters—but the two measures describe different portions of the typeface.

In practice, the x-height is not a fixed universal value but varies between typefaces. Designers often express it as a proportion of the em square or of the cap height. Typefaces with a large x-height present more of the lowercase letter bodies above the baseline, which can improve legibility at small sizes, especially on low-resolution displays. Conversely, a small x-height can produce a more delicate, compact appearance but may reduce readability in small text.

The x-height influences perceived density, color, and tone of a block of text. It interacts with other metrics such as letterforms, stroke contrast, and optical size adjustments. When selecting a font for body text versus display, the x-height is a common consideration for balancing legibility and aesthetic character across sizes and mediums.