Leading

"Leads" redirects here. For the city and metropolitan borough in West Yorkshire, England, see Leeds. For other uses, see Lead (disambiguation).

"Line leading" and "Line lead" redirect here. For the water navigation concept, see Leading line. For other uses, see Lead line (disambiguation).

"Double spacing" redirects here. For double spaces between sentences, see Sentence spacing.

In typography, leading /ˈlɛdɪŋ/ refers to the distance between the baselines of successive lines of type. The term originated in the days of hand-typesetting, when thin strips of lead were inserted into the forms to increase the vertical distance between lines of type. The term is still used in modern page layout software such as QuarkXPress and Adobe InDesign.

In consumer-oriented word processing software, this concept is usually referred to as "line spacing" or "interline spacing."

Origins

The word comes from lead strips that were put between set lines of lead type, hence the pronunciation "ledding" and not "leeding". When type was set by hand in printing presses, slugs or strips of lead of appropriate thicknesses were inserted between the lines of type to add vertical space, improving legibility.

Practices

Leading can be used to enhance the readability of a page or block of text. The standard leading used in printing is usually +2 points for mechanically set body text, or +20% in digital typesetting. In both cases, with a 10 pt font the usual leading is 12 pt, creating a 12/10 ratio, which is considered single spacing. Many typography tests suggest that ideal leading should be equal to 120-145% of the font size.

Line spacing comparison. In many word processors the "single" line spacing is automatically set to 115% or 1.15em (the second column).

Double spacing is not an effective leading to increase readability. Double spacing is an entrenched practice due to the era of typewriters and, in academic settings, to allow the addition of handwritten comments and proofreading. Typewriters had a limited number of options for leading and double spacing was chosen as a default. Double spacing can increase the amount of unused white space on a page and lessen the number of lines on a page. Too much leading can cause continuity problems, as the eyes of the reader are required to travel a greater distance between lines of text.

Text set "solid" (no leading) appears cramped, with ascenders almost touching descenders from the previous line. The lack of white space between lines makes it difficult for the eye to track from one line to the next, makes rivers more obvious, and hampers readability.

Issues

Leading can be affected by a series of issues, all of which can be rectified or used to the printer’s advantage. A leading that is negative (12/10) could be viewed as a hindrance to readability. It would cause the text to be harder to read as lines would be forced together lessening room between lines and hindering readability. However, for short bursts of text a negative leading can enhance the message of the text and can create a more effective text. Negative leading can be affected by ascenders and descenders on certain letters. Letters with high ascenders and low descenders can interfere with one another between lines, if the leading is small enough to allow them to touch one another. Written texts with several portions that demand separate leading can lead to issue of text continuity. Written texts should have a standard leading that does not deviate from page to page. There are instances that call for a change in leading, such as when a block quote is placed within a written text. The lines on the front of a page and the verso (back) should line up vertically, line for line. If there are several leadings contained on one page, this convention can be completely negated. Fonts can also affect the need for leading. No two fonts are exactly alike and for that reason many have characteristics that demand a certain leading. Fonts that are darker require a wider leading that those that are lighter. As well, fonts that are serif should be leaded wider than those that are sans serif. Languages can decide the leading that a printer uses as well. Leading is an important issue to consider when printing as it can enhance readability, but it can also affect the number of pages as larger leadings decrease the number of lines per page. In this way the leading of a page can have a profound effect on the written text.

Examples

This block of text has default leading:

Typography (Greek: typos "form", graphein "to write") is the art and technique of setting written subject matter in type using a combination of typeface styles, point sizes, line lengths, line leading, character spacing, and word spacing to produce typeset artwork in physical or digital form.

The same block of text set with 50% leading is easier to read:

Typography (Greek: typos "form", graphein "to write") is the art and technique of setting written subject matter in type using a combination of typeface styles, point sizes, line lengths, line leading, character spacing, and word spacing to produce typeset artwork in physical or digital form.

The same block of text at 100% leading is again easier to read but makes less efficient use of vertical page space:

Typography (Greek: typos "form", graphein "to write") is the art and technique of setting written subject matter in type using a combination of typeface styles, point sizes, line lengths, line leading, character spacing, and word spacing to produce typeset artwork in physical or digital form.

On the World Wide Web

In CSS, leading is implemented by creating a difference between the content height and the value of the line-height property. Half the leading is called the half-leading. User agents center glyphs vertically in an inline box, which adds half-leading on the top and bottom. For example, if a piece of text is "12pt" high and the line-height value is "14pt", 2pt of extra space should be added: 1pt above and 1pt below the text (this applies to empty boxes as well, as if the empty box contained zero-height text).

Feathering

The leading may be increased to align the bottom line of text on a page in a process known as feathering, carding, or vertical justification.

Bastard fonts

Normal fonts (1, 2) and bastard fonts (3, 4)

In metal typesetting some fonts has default increased or decreased leading. To achieve this a smaller font face is casted on the body of a larger font or vise versa. Such fonts are usually called "bastard" fonts or types. In the notation they are usually written with the face and the body size separated by a slash, like 10/12 that is a 10-point font face on a 12-point body, or 12/10, a 12-point font face on a 10-point body.

See also

• Sentence spacing