X-Height

X-height is the height of lowercase letters measured from the baseline, typically represented by the letter 'x' (which has no ascenders or descenders). It's one of the most important metrics for readability — fonts with taller x-heights appear larger and more readable at the same font size. For example, Inter has a notably tall x-height (x/cap ratio of about 0.72), while Garamond has a shorter x-height (about 0.63). When pairing fonts, matching x-heights ensures that body text appears consistent. A mismatch creates an uneven, jarring appearance where fonts at the same size look different sizes.