Line spacing is the vertical distance between lines of text. Most writers use either double-spaced lines or single-spaced lines—nothing in between—because those are the options presented by word processors.
These habits are obsolete typewriter habits. Originally, a typewriter’s platen could only move the paper vertically in units of a single line. Therefore, line-spacing choices were limited to one, two, or more lines at a time. Single-spaced typewritten text is dense and hard to read. But double-spacing is still looser than optimal.
Most courts adopted their line-spacing standards in the typewriter era. That’s why court rules usually call for double-spaced lines. On a typewriter, each line is the height of the font, thus double spacing means twice the font size. So if you’re required to use a 12-point font, double line spacing means 24 points.
Curiously, the so-called “double” line-spacing option in your word processor doesn’t produce true double line spacing. Microsoft Word’s “double” spacing, for instance, is about 15% looser, and it varies depending on the font. To get accurate spacing, you should always set it yourself, exactly.
For most text, the optimal line spacing is between 120% and 145% of the point size. Most word processors, as well as CSS, let you define line spacing as a multiple. Or you can do the math—multiply your point size by the percentage. (The text in this paragraph has line spacing of 110%. It’s too tight.)
For most text, the optimal line spacing is between 120% and 145% of the point size. Most word processors, as well as CSS, let you define line spacing as a multiple. Or you can do the math—multiply your point size by the percentage. (The text in this paragraph has line spacing of 135%. It looks fine.)
For most text, the optimal line spacing is between 120% and 145% of the point size. Most word processors, as well as CSS, let you define line spacing as a multiple. Or you can do the math—multiply your point size by the percentage. (The text in this paragraph has line spacing of 170%. It’s too loose.)
Word processors have a bewildering number of ways to set line spacing. Don’t be thrown off—it all comes back to the same thing.
How to set line spacing
WordRight-click in the text and select Paragraph from the menu. Go to the menu under Line spacing. Exactly is best—enter a fixed measurement. Single, 1.5 lines, and Double are equivalent to about 117%, 175%, and 233% line spacing, contrary to what their names suggest. Don’t use these—they miss the target zone of 120–145%. Multiple is also acceptable—enter line spacing as a decimal. To get line spacing in the 120–145% range, use a Multiple value of 1.03–1.24. (Not 1.20–1.45—as noted above, Word uses peculiar line-spacing math.) Never use At least, because that gives Word permission to adjust your line spacing unpredictably.
WordPerfectFormat → Line → Height and Spacing. Line spacing in WordPerfect is the Height value multiplied by the Spacing value. (The benefit of this complication may be appreciated by WordPerfect fans. It is lost on me.) I recommend always leaving Spacing at 1.0 and just setting your line spacing with Height. Selecting Height lets you choose from Fixed or At Least. Use Fixed—enter a measurement in the 120–145% range. Don’t use At Least.
by the way
Recall that different fonts set at the same point size may not appear the same size on the page. (See point size for why.) A side effect is that fonts that run small will need less line spacing, and vice versa.
Line spacing affects the length of a document more than point size. If you need to fit a document onto a certain number of pages, try adjusting the line spacing first.
Some lawyers have suggested to me that courts should adopt Microsoft Word’s interpretation of line spacing as the standard. I disagree, for a simple but serious reason. Access to the courts is a fundamental right. Interpreting line spacing according to the quiddities of a commercial software program would imply that parties have to buy a license to that program to comply with the rules and thereby gain access to the courts. But double line spacing in its traditional sense can be implemented with any typesetting program.