Tracking is the uniform adjustment of space between all characters in a selected range of text, such as a word, a line, a heading or an entire paragraph. In typography, it changes the overall density and texture of text without altering the shapes of the letters, and it is controlled in professional tools in units of thousandths of an em.
Tracking is frequently confused with kerning. Kerning adjusts the space between one specific pair of letters, such as A and V, while tracking applies the same adjustment to every pair in the selection. In web development, tracking corresponds to the CSS property letter-spacing.
How tracking changes the space between letters
Every glyph in a font has built-in sidebearings, the small spaces on its left and right edges that the type designer sets for comfortable reading at a particular size. Tracking adds or subtracts the same amount to the space after each character, so the relative rhythm designed into the font is preserved while the whole text becomes looser or tighter.
Because tracking is measured relative to the em, which equals the current font size, the same value scales automatically. A tracking of +20 units adds 20/1000 of an em after each character: about 0.24 points at 12 points and 1.44 points at 72 points. This makes values transferable between sizes, although the visually ideal value still changes with size.
Applications express tracking in different units, which causes confusion when specifications move between design and code. The following table compares the most common conventions.
| Environment | Unit | Equivalent of +50 units |
|---|---|---|
| Desktop publishing software | 1/1000 em | 50 |
| CSS letter-spacing | em or px | 0.05em |
| Interface design tools | Percent of font size | 5 percent |
| Mobile platform text styles | Points or em fractions | Converted per platform |
One technical detail matters on the web: CSS letter-spacing adds space after every character, including the last one, which can make tracked text look slightly off-center. Designers compensate with padding or by accepting the small offset in centered headings.
Typical tracking values by text size and style
The right tracking depends mainly on size, case and weight. Fonts are usually spaced for text sizes, so large display text benefits from tighter tracking and very small text from slightly looser tracking.
| Text situation | Typical tracking | Reason |
|---|---|---|
| Body text, 9 to 14 pt | 0, sometimes +5 to +10 | Fonts are spaced for this range |
| Small captions, below 9 pt | +10 to +30 | Prevents letters from clogging |
| Large headlines, above 36 pt | -10 to -40 | Default gaps look too open at size |
| All capitals and small caps | +50 to +100 | Capitals lack ascender and descender rhythm |
| Light weights at large size | Slightly negative | Thin strokes leave gaps looking wide |
| Reversed text, light on dark | +5 to +20 | Light text appears to spread and fill in |
These ranges are starting points, not rules. Fonts with optical sizes or a variable optical-size axis already adjust spacing for each size, so they typically need much less manual tracking than fonts drawn for a single size.
Tracking compared with kerning and other spacing controls
Typography offers several spacing controls, and each one acts on a different dimension of the text. Knowing which control solves which problem avoids distorting a carefully designed font.
| Control | Acts on | Typical purpose |
|---|---|---|
| Tracking | All character pairs in a range | Overall density and texture |
| Kerning | One specific letter pair | Fix uneven gaps such as AV or To |
| Word spacing | Spaces between words | Adjust line color and justification |
| Leading | Distance between baselines | Vertical rhythm and readability |
| Horizontal scaling | Glyph widths themselves | Distorts letters and is best avoided |
The usual order of work is to choose an appropriate font, set leading and line length, apply tracking for the size and style, and only then fix individual pairs with kerning. Kerning before tracking wastes effort, because a later tracking change alters the whole context of those pairs.
Tracking for legibility and accessibility
Tracking has a direct effect on legibility, the ease of recognizing individual letters, and on readability, the comfort of reading longer passages. Text that is tracked too tightly makes letters touch and merge, while text tracked too loosely breaks words apart into individual letters.
For digital products, the Web Content Accessibility Guidelines (WCAG) 2.1, under success criterion 1.4.12 Text Spacing, require that content remain usable when users increase letter spacing to 0.12 times the font size. Layouts therefore should not depend on a precise tracking value, and text containers should be able to expand.
Some readers, including many people with dyslexia or low vision, report that slightly increased letter spacing makes text easier to read. Evidence on the size of this benefit varies, so the safest approach is a moderate default with room for user adjustment.
Common tracking mistakes
Most tracking errors come from applying one value everywhere or from using tracking to solve a layout problem. The following mistakes are the most common.
- Tightening body text to save space makes paragraphs dark and tiring; editing the copy or the layout is the better solution.
- Untracked all-caps headings look cramped because capitals were designed to sit next to lowercase letters.
- Loosely tracked lowercase text breaks word shapes, which readers rely on for fast recognition.
- Tracking a single line to fix a widow produces visibly uneven density compared with neighboring lines.
- Copying percentage values into CSS without conversion yields spacing ten or a hundred times off.
The idea in brief
Tracking is how close together or far apart all the letters in some text sit. Increasing it spreads the letters out evenly, and decreasing it pulls them closer together, without changing the letters themselves.
Think of people standing in a line. Tracking asks everyone to take the same small step apart or together, while kerning only moves one particular pair who were standing awkwardly. Good tracking makes large titles look tight and polished and small text easy to read.
A practical scenario
A designer prepares a museum exhibition poster. The title is set in a sans-serif typeface at 160 points, a short label above it appears in all capitals at 11 points, and the descriptive text runs at 10 points.
At its default spacing, the large title looks loose and uneven, so the designer applies tracking of -25. The capital label looks cramped, so it receives tracking of +80. The body text is left at zero tracking, because the font was spaced for that size, and only two awkward pairs in the title are kerned afterward.
The finished poster reads as one coherent typographic system: the headline is compact and strong, the label is airy and elegant, and the body text remains comfortable to read at a distance.