What is x-height in typography?

Answer 1

The "x-height" of a typeface is height of lower-case letters. More specifically, this refers to the non-ascender/non-descender letters (ascenders being those with ascending parts that rise above the midline, the tall letters b, d, f, h, k, l,and descenders being those letters with tails that drop below the baseline, typically g, j, p, q, y; this does, of course vary with the design of the typeface: some typefaces will have a descender z, such as many cursive fonts, and other nuances, and some are entirely without descenders. X-height is literally the height of the lowercase letters such as x (obviously), v, w and z. Letters with curves at the top and bottom (c, o, s, e, n, u) can be spoken of as having the same x-height, although technically, rounded letters usually slightly taller than the x, for optical balance.

The x-height of a typeface is important for several reasons. Most importantly, the x-height determines the top/bottom center of mass for a line of type, since in most situations, there are relatively few uppercase letters, and the ascending portions of letters are visually very insignificant. X-heights contribute a great deal to the way a typeface sets. Much of typography is less a matter of objective measurements than it is subjective perception and feel. For example, a typeface with a large x-height is generally easier to read at smaller type sizes, being generally larger and less cramped, while small x-heights can impact legibility. They can also appear somewhat chunkier on the page, since the x-height contributes the majority of a line of type's substance.

On the other hand, type with a large x-height tends to appear to take up more space on a line, making text areas on a page appear somewhat darker and denser in color, and lines may need comparatively more leading (line spacing) to preserve an ideal page color and texture. Large x-heights can also make a typeface look bulky and round.