Line Height Calculator
Set your font size and measure (column width) to get a recommended line height, a characters-per-line reading, and a live preview at those exact settings.
Good typography is invisible. Readers absorb the words, the rhythm of the lines, and the shape of the paragraph without ever noticing the letterforms beneath them — which is exactly why line height matters so much. Too tight and the lines collide; too loose and the paragraph stops reading as a single unit. Somewhere between 1.4 and 1.8, at a measure of 45 to 75 characters, the eye travels comfortably from the end of one line to the start of the next.
Rules of Thumb
Measure: 45–75
Characters per line. Under 45 the eye works too hard jumping lines; over 75 it loses its place returning to the next one.
Bigger type, less leading
Display type needs a tighter ratio (1.05–1.2) because the letterforms already create space. Small body copy wants 1.5–1.8.
Use unitless values
line-height: 1.6 scales with the font it is applied to. Pixel values do not, and percentages inherit awkwardly.