Intypography, thex-height, orcorpus size, is the distance between thebaseline and themean line of lowercase letters in atypeface. Typically, this is the height of the letterx in the font (the source of the term), as well as the lettersv,w, andz. (Curved letters such asa,c,e,m,n,o,r,s, andu tend to exceed the x-height slightly, due toovershoot;i has a dot that tends to go above x-height.) One of the most importantdimensions of a font, x-height defines how high lowercase letters withoutascenders are compared to thecap height of uppercase letters.

Display typefaces intended to be used at large sizes, such as on signs and posters, vary in x-height. Many have high x-heights to be read clearly from a distance. This, though, is not universal: some display typefaces such asCochin andKoch-Antiqua intended for publicity uses have low x-heights, to give them a more elegant, delicate appearance, a mannerism that was particularly common in the early twentieth century.^[2][3] Many sans-serif designs that are intended for display text have high x-heights, such asHelvetica or, more extremely,Impact.

Medium x-heights are found on fonts intended for body text, allowing more balance and contrast between upper- andlowercase letters and a brighter page. They then increase again foroptical sizes of fonts designed for small print, such as captions, so that they can be clearly read printed small.^[4][5]

High x-heights on display typefaces were particularly common in designs in the 1960s and '70s, whenInternational Typeface Corporation released popular variations of older designs with boosted x-heights; notable examples of this trend includeAvant Garde Gothic andITC Garamond.^[6][7] More recently, some typefaces such asMrs Eaves,Neutraface andBrandon Grotesque have been issued with distinctively low x-heights to try to create a more elegant appearance. While computers allow fonts to be printed at any size, professional font designers such as Adobe issue fonts in a range of optical sizes optimized to be printed at different sizes.^[8] As an example of this, Mrs Eaves exists in two versions: an original style intended to give an elegant, bright appearance, and a less distinctive 'XL' design intended for body text.^[9]

Some research has suggested that while higher x-heights may help with reading smaller text, a very high x-height may be counterproductive, possibly because it becomes harder to identify the shape of a word if every letter is nearly the same height. For the same reason, some sign manuals discourage all-capitals text.^[10][11][12]

Incomputing one use of x-height is as a unit of measurement inweb pages. InCSS andLaTeX the x-height is called anex. The use of ex in dimensioning objects, however, is less stable than use of theem acrossbrowsers.Internet Explorer, for example, dimensions ex at exactly one half of em, whereasMozilla Firefox dimensions ex closer to the actual x-height of thefont, rounded relative to the font's currentpixel height. Thus, the exact ratio of ex to em can vary by font size within a browser if the determined values are rounded to the nearest whole unit. For example, a browser calculating an x-height of 45% on a font 10 pixels tall may round ex to either 4 pixels or 5 pixels or leave it at 4.5 pixels.

Lowercase letters whose height is greater than the x-height either havedescenders which extend below thebaseline, such asy,g,q, andp, or haveascenders which extend above the x-height, such asl,k,b, andd. The ratio of the x-height to thebody height is one of the major characteristics that defines the appearance of a typeface. The height of the capital letters is referred to ascap height. x-height is most important in regular designs, such as most serif and sans-serif designs;script typefaces that mimic irregular handwriting and calligraphy may not have a consistent x-height across all letters.

• En (typography)
• Small caps
• Typeface anatomy

• Definition of x-height at typophile.com
• In the search of ideal line-height

• Typography

• Articles with short description
• Short description is different from Wikidata