Kerning vs tracking vs leading

Where the words come from

All three terms come from metal type, when every letter was a small block and spacing meant physically adding or removing material. Kerning was the part of a letter that overhung its block so it could tuck under or over a neighbour, as when the arm of a T reaches over a lowercase o. Leading, pronounced like the metal, was literally strips of lead placed between lines of type to push them apart. Tracking arrived later with phototypesetting and digital type, as a single setting that loosens or tightens a whole run of letters at once. The old vocabulary survives because the problems have not changed. Letters still have awkward pairs, capitals still sit too close together, and lines of text still need room between them to be read comfortably.

How each is measured

Kerning and tracking are measured in fractions of the em, the current font size, usually thousandths, so a value stays proportional when the text is scaled. A well made font already contains a kerning table with adjustments for hundreds of letter pairs, and Matthew Butterick's Practical Typography advises always leaving that built in kerning switched on. On the web, the CSS letter-spacing property is the equivalent of tracking. Leading is measured from one baseline to the next, either in points or as a multiple of the font size; in CSS it is called line-height. Butterick recommends line spacing between 120 and 145 percent of the point size for most text, and adding around 5 to 12 percent extra letterspacing to text set in all capitals or small capitals, while leaving lowercase body text alone.

When each one matters

Kerning matters most at large sizes. At body text size nobody notices a slightly loose pair, but in a 120 pixel headline the gap between a capital W and an A, or the space around a T, becomes an obvious hole that can even appear to split a word in two. Tracking matters for capitals and for very small or very large text: capitals were designed to sit beside lowercase letters and feel cramped when set together, while display headlines sometimes look better slightly tighter. Leading matters for anything longer than a single line. The Web Content Accessibility Guidelines treat spacing as an accessibility issue too: success criterion 1.4.12 requires that web content still works when readers increase line height to 1.5 times the font size and letter spacing to 0.12 times it.

Common mistakes

The most common mistake is tracking out lowercase body text to fill a line or to look airy, which breaks up word shapes and slows reading. Close behind is tightening a headline so much that letters touch or overlap, which looks deliberate on a monitor and becomes a smudge on a cheap print. Leading causes two opposite problems. Multi line headlines set with body text leading look disconnected, because large type needs proportionally less space between lines, while paragraphs set solid, with leading equal to the font size, look dense and make it easy to reread the same line. People also confuse leading with paragraph spacing: extra space between paragraphs belongs after a paragraph, not added to every line inside it. Finally, fixing spacing letter by letter often means the font itself is the wrong choice.

Where spacing shows up in the flyer builder

The flyer builder does not offer kerning, tracking or leading controls. The text controls are Size, which picks from the theme's type ramp, Font, Colour, Weight, Align and Drop shadow, and nothing else. Spacing therefore comes from the font itself and from the way each design lays out its text, so the letter and line spacing a reader sees are decided by the font choice and the design rather than by a number typed into a box. The practical levers are the ones that change those inputs. Switching the global font, or overriding the font on a single slot, brings a different set of proportions, and there are 27 families to choose from. Choosing a different size from the ramp changes how tight a headline looks. And shortening copy is often the most effective fix, because a headline that has room to sit on one line never has a leading problem.

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