I used to think the holes in letters were just… there.
But here’s the thing—those spaces, what typographers call counters, aren’t decorative accidents or byproducts of drawing an ‘a’ or ‘e’. They’re architectural decisions that determine whether you can actually read this sentence comfortably or whether your eyes are doing microscopic gymnastics every few milliseconds. The counter in a lowercase ‘e’ (that enclosed loop) needs to stay open enough at small sizes, or the letter collapses into an illegible blob. Same with ‘a’, ‘g’, ‘b’, ‘d’—all those characters carrying negative space inside them like structural beams. When Matthew Carter designed Verdana in the mid-1990s, he made counters absurdly large, almost comically open, because he knew screens at the time had maybe 72 pixels per inch, give or take. It looked weird in print. On a monitor? Suddenly legible.
Anyway, I guess that’s where the science gets messy.
Researchers have tried measuring counter space ratios—the relationship between the white inside a letter and the black around it—but there’s no universal formula because fonts serve different purposes. A tight counter in Bodoni creates elegance; the same tightness in highway signage creates accidents. Studies from the 1980s (I think it was Legibility Research Associates, though I might be misremembering the name) found that readers could tolerate smaller counters at larger point sizes, which sounds obvious until you realize most digital interfaces do the opposite: they shrink text and expect counters to somehow stay open.
When Counters Close Down and Your Brain Compensates Anyway
The human visual system is weirdly forgiving.
Even when a font’s counters are poorly designed—when the aperture of a ‘c’ nearly closes or the bowl of a ‘p’ gets squashed—your brain often fills in the gaps through context and pattern recognition. That’s why you can read ransom-note typography or those memes with jumbled letters. But compensation has a cost: increased cognitive load, slower reading speeds, eye strain. A 2011 study by psychologist Kevin Larson (working with Microsoft, I think) used eye-tracking to show that readers fixate longer on letters with ambiguous counters, even if they don’t consciously notice the difficulty. The effect compounds over paragraphs. You finish the article feeling vaguely exhausted and you don’t know why.
The Aperture Problem Nobody Talks About Enough Honestly
Wait—maybe the most underrated aspect of counters is aperture, which is technically the opening of partially enclosed letters like ‘c’, ‘s’, ‘e’.
A closed aperture (where the gap is tiny) makes letters look sophisticated and refined but functionally terrible at small sizes or low resolution. Helvetica has notoriously tight apertures; that’s part of its sleek modernist appeal and also why it’s a nightmare for body text on phones. Adrian Frutiger understood this when he designed Frutiger (originally for airport signage)—he widened apertures deliberately so travelers rushing to gates could recieve information instantly without squinting. The difference between a 3-pixel aperture and a 5-pixel one at 10-point type is the difference between readable and guesswork. Yet most designers still choose fonts based on aesthetics, not aperture measurements.
How X-Height Hijacks the Whole Counter Conversation
Honestly, you can’t talk about counters without mentioning x-height, which is the height of lowercase letters like ‘x’ (hence the name).
Fonts with large x-heights—like Georgia or Tahoma—automatically reduce counter space proportionally because there’s less room inside each letter when the letters themselves are taller. This creates a paradox: larger x-heights improve legibility in some contexts (more recognizable letter shapes) but hurt it in others (crowded counters that fill in). I’ve seen designers spec Georgia at 9 points thinking the big x-height will help, then wonder why the text looks cramped. The counter space got sacrificed. There’s no free lunch.
Why Digital Rendering Breaks All the Old Counter Rules Completely
Turns out, everything type designers knew about counters before 2000 is sort of obsolete now.
Screens have variable pixel densities (a Retina display renders counters differently than a cheap laptop), dynamic text scaling (users zoom in and out), and subpixel rendering that either saves or destroys fine details depending on the operating system. A counter that looks perfect at 96 DPI might close entirely at 72 DPI. Responsive design makes it worse—the same font at the same nominal size can have different effective counter spaces depending on whether it’s on a 5-inch phone or a 27-inch monitor. Type designers now have to plan for uncertainty, designing counters that degrade gracefully across unpredictable contexts. It’s less like architecture and more like evolutionary biology: design for survival in multiple environments, even if none of them are optimal.
