Leading as Structure

Leading — the vertical space between lines of text — is the most impactful spatial decision in typography, and the one most frequently treated as an aesthetic option. It is not. Leading is structural. It determines whether text feels dense or spacious, rushed or considered. It controls the pace at which the eye moves through content. Getting it wrong makes text hard to read regardless of typeface quality.

What leading does

When lines of text are set too close together, the eye struggles to track across a line and return to the correct position on the next. The text feels crowded. Reading requires effort rather than flowing naturally. Conversely, when lines are set too far apart, the text loses cohesion — the eye has to travel too far to make the connection between consecutive lines, and the page starts to feel empty and disjointed.

The correct line height creates a channel for the eye: wide enough to track comfortably, tight enough to maintain the logical connection between lines. At that setting, reading becomes invisible — the text simply communicates.

The relationship between font size and line height

Line height is typically expressed as a multiplier of the font size. For body text at 16px, a line height of 1.5 gives 24px of vertical rhythm. A line height of 1.4 gives 22.4px. These differences seem small in isolation. In a paragraph of several lines, they are immediately perceptible.

For body text, a range of 1.4–1.6 is a reasonable starting point — but the right value depends on the specific typeface as much as the context. A typeface with a tall x-height needs more leading than one with a small x-height at the same point size, because the ascenders and descenders of adjacent lines sit closer together. Longer line lengths also require more leading — the eye has further to travel at the end of each line, and more leading compensates. Shorter line lengths can tolerate tighter leading because the return journey is shorter. For headings and display text, leading should tighten substantially: 1.1–1.3 is common at large sizes, because display text is rarely more than two or three lines and the visual impact of the size calls for compactness.

When to adjust

Increase leading when: text is long-form and will be read at length; the line length is wide; the typeface has a tall x-height that makes lines feel close even at standard settings. Decrease leading when: text is display or headline size; text is short (a label, a caption, a button) where visual compactness is appropriate; the column is very narrow.

See Measure and the Reading Line for how line length interacts with leading decisions. See Paragraph Rhythm for the relationship between line height and inter-paragraph spacing.