Leading, which is pronounced ‘led-ding’, is the term used in typography to describe the space between lines of text. It is measured baseline-to-baseline, in points.
Leading is also called line spacing or vertical spacing. It is not the same as tracking, which refers to the horizontal spacing between characters. The term dates back to metal typesetting when thin strips of lead were manually inserted between lines (slugs) of type.
- Primary leading is the leading utilized in the main body of text, or in a particular set of lines.
- Secondary leading is the amount of leading used to separate paragraphs, blocks of copy, or specific lines.
How much leading should be used
Leading needs to be set in proportion to the line length, the point size, and the characteristics of the typeface that is used. Closer leading fits more text on the page but decreases legibility. If too little leading is used, the lines may touch or overlap one another. Text is ‘set solid’ when no leading is used.
- As a general rule, leading should be about 120% of the point size; for example, 10-point type with 12 points of leading. This is described as 10/12 (ten on twelve) and it is the default setting in applications like Adobe InDesign.
- Long lines of text may require extra leading.
- Boldface or sans serif type requires more leading.
- Type set at very small sizes (8 points or below) may require extra leading.
- For display type (e.g. a headline used on a poster) less leading is often used.