What Is an Aperture in Typography?
By Maya Chen, lettering designer and type educator · Checked by Jordan Hale · · How we review content
Say a letter has a pocket of white inside it. The counter is that pocket. The aperture is the way into it. On a c it is the gap between the two terminals; on an e it is the opening below the crossbar; on an s there are two, one at the top left and one at the bottom right; on a capital G it is the gap leading into the bowl. When designers talk about a typeface being “open” or “tight,” they are usually talking about its apertures.
Open and closed apertures
An open aperture is wide: the terminals pull back, so you can see in. A closed aperture is narrow: the terminals curl round until they nearly touch the bowl, as in the lowercase a, c and e of Helvetica or Univers. The same letters in Frutiger, Myriad or Open Sans open outward and look noticeably less cramped.
| Quality | Open | Closed |
|---|---|---|
| Typical faces | Humanist sans-serifs, text serifs such as Charter | Grotesque and neo-grotesque sans, some geometric faces |
| Feels | Friendly, readable, spacious | Compact, even, authoritative |
| At small sizes | Letters stay distinct | c and e can approach o and a |
| Common use | Body text, signage, interfaces | Logos, headlines, corporate branding |
The effect is easiest to see by comparing c and o in two fonts at a very small size. If the c nearly closes, the letters merge, and a reader must rely on the surrounding word to understand them. The case is strongest on road signs and small printed labels, where open apertures are a deliberate choice for legibility at a glance.
Aperture and the terminal
The shape of the terminal directly controls the aperture. An angled terminal that follows the stroke direction produces an open aperture, while a horizontal or vertical terminal cuts the stroke back across itself and closes it. So the terminal decision and aperture decision are two views of the same detail. Designers also tune the aperture through the weight: in bold weights the strokes thicken into the opening, so the aperture is narrowed unless the designer redraws it.
Aperture and the x-height
Tall x-heights tend to give letters more room, and the apertures of c, e and s are therefore generous in fonts with large lowercase. Low x-heights leave less vertical room, so the apertures of the small letters tend to be tighter, or the designers compensate by making them wider.
Aperture in lettering
When you draw letters by hand the aperture is where you control mood. If you want a casual, friendly look, leave the c and e apertures wide, with the terminals ending well before the bowl. If you want a heavy, compressed, poster-like feel, close them. Whatever you choose, make every aperture in the word match: a very open c next to a nearly closed e looks like two different alphabets.
A useful drill is to draw c, e, a, s in rows with a deliberately wide aperture, then deliberately narrow, then check which looks more like a consistent set when seen from a distance. The result will tell you more about your own hand than any rule.
In brush lettering, the aperture of e is easy to ruin by pressing too hard on the downstroke, which fills the eye. Lift the pressure for the loop of the e and keep the thick part for the following downstroke. The hand lettering for beginners guide has more on stroke control.
Aperture in fancy text
Unicode styles inherit the aperture of the font drawing them. Letters from the small text generator are drawn at small sizes where open apertures matter more, which is one reason tiny Unicode forms can be hard to read. The same cause explains why a fancy style legible on a phone in one font may be muddy in another.
Common confusions
- Aperture is not the counter. The counter is the white space, the aperture is its opening.
- Not the same as spacing. The gap between two letters is spacing, not aperture.
- Photography meaning. In photography, aperture is the lens opening. The typographic term shares the idea of an opening, but is unrelated.
Frequently asked questions
Which letters have apertures?
Is a larger aperture always better for legibility?
Why is the aperture of e often slanted?
Related terms
- What Is a Counter in Typography?A counter is the empty space enclosed or partly enclosed by a letter's strokes, such as the hole in o, the eye of e or the opening under the arch of n. Counters shape how dark, open and readable a letter looks.
- What Is a Terminal in Typography?A terminal is the end of a stroke that does not end in a serif. It can be flat, angled, rounded, a ball, a teardrop or a flick, and the choice gives a typeface much of its personality, from formal to friendly.
- What Is x-height?The x-height is the height of the lowercase letters that have no ascenders or descenders, such as x, a, e and o, measured from the baseline to the top of the letter. It is the main reason two fonts at the same size look bigger or smaller.
- What Is Sans Serif?Sans serif describes a typeface whose letters have no serifs, the small finishing strokes at the ends of stems. The term is French for "without serif"; Helvetica, Arial and Futura are common examples.
- Typography & Lettering GlossaryThe Typography & Lettering Glossary defines twenty terms that type designers and letterers use every day, from kerning and x-height to serif, ligature and blackletter. Each entry gives a precise definition, then shows what the idea means for hand lettering and for the styled Unicode text our generators produce.
- What Is an Ampersand? Origin of the & SymbolThe ampersand is the symbol & meaning "and". It began as a handwritten ligature of the Latin word et, its name comes from the old schoolroom phrase "and per se and", and many typefaces draw it in strikingly elaborate ways.