The x-height is the height of lowercase letters without ascenders or descenders, measured from the baseline to the top of the “x”. Its upper limit is known as the mean line, and it largely determines the apparent size of a font.
Where to see it
The x-height is measured on letters such as “x”, “a”, “n”, “u” or “z”, whose tops align on the same horizontal line. The ascenders of “b” or “h” rise above it, while the descenders of “p” or “g” drop below the baseline.
Why this detail matters
The x-height directly shapes the readability and look of a typeface:
- At the same point size, a font with a large x-height looks bigger and stays readable at small sizes and on screen;
- A small x-height leaves more room for ascenders and descenders, giving a more elegant, airy text, often associated with classic typefaces;
- The ratio between x-height and cap height is one of the first criteria for pairing two fonts harmoniously.
Related term
The cap height is the height of capital letters, measured from the baseline to the top of a flat letter such as the “H”.
Anatomy glossary
Ascender, Descender, Sidebearing, Joint, Axis, Bar, Beak, Bowl, Loop, Set width, Counter, Serif, Stem, Leg, Minim, Baseline, Eye, Belly, Foot, Point, Tail, Cross stroke, Terminal; X-height, X-height, Cap height, Body; Mean line, Ear, Spur, Ball terminal, Ligature, Apex, Vertex, Arm, Shoulder, Spine, Em dash, Thick stroke, Hairline, Bracket, Bounding box