What line spacing should a printed book use?

Between 120 and 145 percent of the type size, which is Butterick's range for text generally. Most trade books sit around 130 percent: an 11-point face on about 14 points of leading. Set it as a multiplier of the type size rather than as a fixed measurement, so that changing the type size carries the leading with it.

Is single spacing wrong for a book?

Yes, for body text. A word processor's Single is roughly 115 percent of the type size or less, which is tighter than the readable range, and Double is far looser than any book uses. Both are typewriter settings rather than typographic ones. Neither number lands in the range a book wants, which is why manuscripts set at either look wrong when printed.

Does line spacing depend on line length?

Yes, and this is the part usually left out. A long line needs more leading, because after each line the eye has to travel back and find the start of the next one, and a wider gap gives it a clearer channel to land in. A narrow column can be set tighter. Bringhurst treats leading as something that should respond to the measure rather than being fixed once.

What is a good measure for a book page?

Bringhurst's range for single-column text is 45 to 75 characters a line, with 66 as the ideal. Below 45 the reader returns too often and the rhythm breaks up; above 75 the return becomes unreliable and lines get re-read. Measure is set by the margins and the type size together, not by the trim size alone.

Does the typeface change how much leading I need?

It does. Two faces at the same point size can have visibly different letter sizes, because what the point size measures is not the height of the letters. A face with a large x-height fills more of the line and wants more space above and below; a small-x-height face can be set tighter at the same nominal size.

Should ebooks use the same line spacing as print?

Set a sensible default and let the reader override it. In a reflowable ebook the reading system controls the type size and often the line spacing, and readers change both. A percentage-based value degrades gracefully when they do; a fixed point value does not.

How much line spacing does a book need?

Ask what line spacing a book should use and you get a number. The number is not wrong, but on its own it is not usable, because the correct leading depends on how long the lines are, and how long the lines are depends on the margins and the type size.

That coupling is the whole subject. Everything else is arithmetic.

The range

Butterick’s rule for text: line spacing between 120 and 145 percent of the point size.

An 11-point book therefore wants something between about 13.2 and 16 points of leading. Most trade books sit near the middle, around 130 percent, which is where the Nueel defaults land.

The typewriter is why the defaults are wrong. On a mechanical typewriter the platen advanced by one fixed step regardless of the type, and there was no type size to speak of — the machine had one. Both “single” and “double” are descriptions of that ratchet, not of anything a compositor would recognise, and they survived into word processors because the interface was modelled on the machine it replaced.

Word processor presets miss on both sides. Single is around 115 percent or less, tighter than the readable range and a direct inheritance from typewriters, where the platen advanced by one fixed step. Double is looser than any published book, and exists because manuscripts were double-spaced to leave room for an editor’s pencil. Neither is a typographic value; both are mechanical ones.

Set leading as a multiple of the type size rather than as a fixed number of points. Then changing the type size later, which you will do when the page count needs to move, carries the leading with it instead of silently tightening the page.

Why one number cannot be right for every page

Leading does a specific job. At the end of a line, the eye has to travel back across the full measure and land on the start of the next one. It has no landmark to aim at. What guides it is the horizontal channel of white space between the lines.

Make the lines longer and the return journey gets harder, so the channel has to be wider. Bringhurst treats leading as something that should respond to the measure for exactly this reason, rather than being chosen once and applied everywhere.

So the practical form of the rule:

Measure	Leading
Narrow, 45 to 55 characters	Toward 120 percent
Comfortable, 60 to 70 characters	Around 130 percent
Wide, 75 characters or more	Toward 145 percent, or reduce the measure instead

The last row is the one worth acting on. If a page needs leading past 145 percent to stay readable, the real problem is that the line is too long, and the fix is wider margins or larger type rather than more air between the lines.

Bringhurst’s range for single-column text is 45 to 75 characters a line, with 66 as the ideal. Our margins guide covers how the margins produce that number.

The type size is not the letter size

Two faces set at 11 point can have letters of visibly different size, because the point size measures the body the letters sit on rather than the letters themselves. What varies is the x-height, the height of a lowercase x.

A large-x-height face fills more of the line vertically, so the same leading leaves less visible space and the page reads tighter. A face with a small x-height at the same nominal size can be set closer without crowding.

This is why the range is a range rather than a number, and why swapping the typeface is a reason to look at the leading again. Butterick’s version: fonts that run small need less line spacing, and fonts that run large need more.

What it costs

Leading is the setting that most cheaply changes a book’s length, which makes it tempting to use as a page-count control.

At 130 percent an 11-point face gives roughly 14.3 points a line. Drop to 120 percent and it gives 13.2. Over a 300-page book, that difference is worth something like 20 pages, which is a real change to the spine width and the printing cost.

It is a legitimate lever, but it is the wrong one to reach for first. A book squeezed to 120 percent on a wide measure has been made cheaper in a way readers feel without diagnosing. If the page count has to come down, the trim size usually gives more room with less damage.

The setting that looks like a single number is really a relationship between three: type size, measure and leading. Change any one and the other two are worth a second look.

Sources

Matthew Butterick, Line spacing in Practical Typography — the 120 to 145 percent range, and the note on faces that run small or large
Robert Bringhurst, The Elements of Typographic Style — leading as a response to the measure, and the 45 to 75 character line with 66 as the ideal
Google Fonts, Justification and hyphenation — how the constraints of metal type shaped conventions still in use

Common questions

What line spacing should a printed book use?: Between 120 and 145 percent of the type size, which is Butterick's range for text generally. Most trade books sit around 130 percent: an 11-point face on about 14 points of leading. Set it as a multiplier of the type size rather than as a fixed measurement, so that changing the type size carries the leading with it.
Is single spacing wrong for a book?: Yes, for body text. A word processor's Single is roughly 115 percent of the type size or less, which is tighter than the readable range, and Double is far looser than any book uses. Both are typewriter settings rather than typographic ones. Neither number lands in the range a book wants, which is why manuscripts set at either look wrong when printed.
Does line spacing depend on line length?: Yes, and this is the part usually left out. A long line needs more leading, because after each line the eye has to travel back and find the start of the next one, and a wider gap gives it a clearer channel to land in. A narrow column can be set tighter. Bringhurst treats leading as something that should respond to the measure rather than being fixed once.
What is a good measure for a book page?: Bringhurst's range for single-column text is 45 to 75 characters a line, with 66 as the ideal. Below 45 the reader returns too often and the rhythm breaks up; above 75 the return becomes unreliable and lines get re-read. Measure is set by the margins and the type size together, not by the trim size alone.
Does the typeface change how much leading I need?: It does. Two faces at the same point size can have visibly different letter sizes, because what the point size measures is not the height of the letters. A face with a large x-height fills more of the line and wants more space above and below; a small-x-height face can be set tighter at the same nominal size.
Should ebooks use the same line spacing as print?: Set a sensible default and let the reader override it. In a reflowable ebook the reading system controls the type size and often the line spacing, and readers change both. A percentage-based value degrades gracefully when they do; a fixed point value does not.