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/ˈbeɪs.laɪn/

Baseline

noun · typography

The invisible horizontal line on which the main body of each letter sits and from which descenders hang.

What it is

The baseline is the single most important reference line in a typeface. Capital letters, the x-height body of lowercase letters, and the feet of most glyphs rest precisely on it; the tails of letters such as g, j, p, q, and y — the descenders — drop below it. Rounded letters such as o and e are drawn to overshoot the baseline very slightly, sitting a hair below it so they appear optically aligned with the flat-bottomed letters beside them.

Because every glyph is positioned relative to the baseline, it is the line typographers measure from when setting type. Point size, leading, and vertical alignment are all defined as distances between baselines. A baseline is a property of a single line of type; when many baselines are spaced at a regular interval across a page, they form a baseline grid — a related but distinct concept.

The word "Type" sitting on a baseline with the descender of the letter p dropping below itTypecap linebaseline
Letters rest on the baseline (orange); the descender of "p" drops below it.

Etymology

The term descends from the ruled lines of manuscript and the metal body of foundry type, where each sort was cast so its printing face aligned to a common foot. "Base line" as a typographic term was standardised in the twentieth century; Robert Bringhurst treats it as foundational vocabulary in The Elements of Typographic Style (1992), and Jan Tschichold's writings on letterform construction use the same reference frame.

Examples in use

"Align the small-caps to the baseline of the running text, not to its cap height." A type designer specifies overshoot relative to the baseline so curved letters read as level. In digital layout, CSS exposes a vertical-align: baseline keyword precisely because the baseline is the default datum to which inline elements are aligned.

See also: Baseline grid · Measure · Typographic grid · Baseline grid overlay

References

  1. Bringhurst, Robert. The Elements of Typographic Style, 3rd ed. Hartley & Marks (2004). ISBN 978-0-88179-206-5.
  2. Tschichold, Jan. The Form of the Book. Hartley & Marks (1991). ISBN 0-88179-116-4.
  3. Lupton, Ellen. Thinking with Type, 2nd ed. Princeton Architectural Press (2010). ISBN 978-1-56898-969-3.

Sarah Chen

Founder of Grid Maker Pro. Classical portrait painter (BA Fine Arts). Writes about composition, drawing methods, and the art-history claims that don't survive measurement.

Updated · Methodology