Choosing an appropriate amount of leading is an essential part of setting professional-quality type. And in InDesign Type: Professional Typography with Adobe InDesign, Third Edition, type expert (and esteemed CreativePro/InDesign Magazine author) Nigel French devotes a whole chapter to the issue of leading. You can download a PDF of the leading chapter and check out a brief sample below.
Also, if you order a copy of InDesign Type very soon (prior to 11:59 p.m. Eastern Standard Time on April 8, 2014), you can use the coupon code MARCHMAYHEM and get 35% off (or 45% off when you order two titles)!
Excerpted from InDesign Type: Professional Typography with Adobe InDesign, Third Edition by Nigel French. Copyright © 2014. Used with permission of Pearson Education, Inc. and Adobe Press.
Getting the Lead Out
When it comes to leading there’s no “one size fits all.” Tight leading increases the density of the type and gives it authority. But if you go too tight, your type looks claustrophobic and the descenders of one line collide with the ascenders of the next. Loose leading can create a luxurious look. But if it’s too loose, the lines of type look like individual strips rather than cohesive paragraphs and the type is made less readable. This is especially true if the leading value is greater than the size of the space between the paragraphs.
Leading is measured in points from one baseline to the next. The leading value includes the point size of the typeface and the actual space between the lines. Thus, 10-point type with 12 points of leading really means two points of space between each line. This is written 10/12, and spoken “10 on 12.” Other common type size and leading combinations for print body text are 9/11, 11/13, and 12/15.
How Much Is Enough?
Bad leading makes your text harder to read because the eye has trouble locating the next line of type. Choosing an appropriate amount of leading depends on several variables:
The nature of the text. While text intended for continuous reading benefits from some breathing space, a short burst of advertising copy or a title might be more effective if the lines are tightly leaded.
Type size. As type size increases, you will want proportionally less leading. With display sizes, the same relative amount of space between the lines appears larger, so much so that it’s common to use negative leading for display type.
The width of the column. Increase leading as you increase column width, or measure. Increasing the leading anywhere from 0.5 point to 2 points improves readability by keeping the lines distinct and preventing the eye from dropping off to the line below or doubling back to reread the same line.
The width of the column gutters. Leading, like all type attributes, needs to work in harmony with everything else on the page. The width of the column gutters should be the same as the leading value or a multiple thereof. If the gutters are too small, there will be a tendency to read across the columns; too large and the separate columns will look unconnected.
The size of the word spaces. A general rule is that your leading should be wider than your word spaces to ensure that the eye moves along the line rather than down the lines. Justified type in narrow columns, such as in newspapers, may result in word spaces larger than the leading. This causes the eye to jump to the next line rather than to the next word. In such situations, extra leading ensures that the space between the lines is at least as wide as the space between the words. Better still, don’t set justified type in narrow columns.
The color of the background. We’re used to reading black type on white paper, so when we use the opposite, we’re guaranteed to get attention. However, reversed type tends to “sparkle,” making it harder to read. A slight increase in leading can compensate. In addition, if you’re working in print, avoid delicate serifs and consider using a heavier weight.
The characteristics of the typeface. Typefaces with larger x-heights are perceived as bigger than other typefaces at equivalent sizes. The lowercase letters are large relative to the size of the overall character, and thus require more leading.
Didone (also called Modern) typefaces that have a strong vertical stress, like Bodoni, guide the eye down the page rather than across the line. Adding more leading with these typefaces keeps the eye tracking horizontally rather than vertically.
Typefaces that combine a low x-height with particularly tall ascenders require special treatment. The low x-height begs suggest tighter leading, but tighter leading might cause the ascenders and descenders to collide. Much depends on the characters themselves. If you’re working on display type, rewording—if you have editorial license—might make all the difference. Let common sense prevail, and be open to the possibility that colliding ascenders and descenders might even look good in certain situations.
Typefaces with small x-heights appear to have more horizontal space between lines and thus require less leading. Bold and Semibold typefaces benefit from extra leading to prevent the type color—the density of the letterforms as a block—from appearing too heavy. Type in all caps requires less leading because the absence of descenders makes the lines appear farther apart.
Screen Leading (Line Height)
The W3C accessibility guidelines recommend a line height of 1.5 ems. While this is a good starting point, it’s not a figure that should be adhered to slavishly. Just as with print, optimal line height onscreen is a nuanced thing, and should factor in the size of the type, the length of the line, the x-height of the typeface, and the perceived preferences of the audience. While it’s broadly true that line height onscreen will be more than its equivalent in print (in part because line lengths onscreen tend to be longer), all of the factors discussed above are as applicable to screen typography as they are to print typography.