What Is Cap Height?
Cap height is the height of a typeface's uppercase letters, measured from the baseline to the top of a flat capital like "H" or "E." It is usually shorter than the ascender height. Cap height matters when aligning capital letters with logos, icons, or other capitals across a layout.
Round capitals like "O" and pointed ones like "A" are usually drawn slightly taller than flat capitals (overshoot) so they look the same height to the eye.
Comparing cap height to x-height reveals a font's proportions: a small x-height relative to cap height reads as classical, a large one as modern and sturdy.