Tracking and Optical Space
Letter spacing is almost always wrong when it has been touched. The exceptions reveal a precise principle: tracking works at the extremes, not in the middle.
Tracking — the uniform adjustment of space between all characters in a block of text — is the most misused tool in typography. It is frequently applied to body text to make text feel more “airy” or more “compact”, and in almost all cases this makes the text harder to read. Well-set body text uses the spacing the typeface designer intended. Tracking at reading sizes is nearly always a mistake.
The rule about the middle
Typeface designers spend significant effort calibrating the default spacing between characters at the sizes their typeface is designed to be used at. This spacing is not arbitrary — it is tuned for reading comfort at the relevant size. Adding tracking to body text disrupts this calibration, creating space between letters that the typeface’s internal logic doesn’t account for. The words stop holding together visually. Reading slows.
The rule is: don’t track body text. The default spacing is correct. If you feel the need to adjust it, the problem is likely something else — font choice, leading, or measure — not letter spacing.
When to increase tracking
Display and headline text is set at sizes the typeface may not have been specifically optimised for. At large sizes, the default spacing often appears too tight — letters seem to crowd each other because optical perception of distance changes with scale. Increasing tracking at display sizes compensates for this optical compression. A value of 0.02em to 0.05em is often enough. The test is whether the words still hold together while the letters breathe.
All-caps text almost always needs positive tracking. The absence of ascenders and descenders reduces the natural spacing cues that help the eye move through lowercase text. Adding 0.05em to 0.1em to all-caps text restores readability. See Display Type for how tracking adjustments scale at headline sizes.
When to decrease tracking
At very small sizes — captions, footnotes, label text below 11px — tight tracking can improve legibility by helping letters cluster into recognisable word shapes. This is the opposite of the display case: at very small sizes, letters need to be held together rather than given room. A slight negative tracking (−0.01em to −0.02em) can help, though the primary solution to small-size legibility is usually choosing a typeface designed for small sizes rather than adjusting tracking of one that isn’t.