Fonts for dyslexia: do they actually work?

The promise of dyslexia fonts

Over the past fifteen years, several fonts have been designed specifically for dyslexic readers. The idea is appealing: if dyslexic people struggle to read standard fonts, perhaps a specially designed font could make reading easier. Three fonts have gained the most attention:

• OpenDyslexic — a free, open-source font with weighted bottoms (heavier at the base of each letter), designed to prevent letters from appearing to rotate or flip. It's the most widely used dyslexia font, available as a browser extension and built into some reading apps.
• Dyslexie — a commercial font created by Christian Boer, a Dutch graphic designer with dyslexia. It uses varied letter heights, increased spacing, and weighted bottoms to make each character as distinct as possible.
• Lexie Readable (formerly Lexia Readable) — a free font based on Comic Sans but refined for better readability. It retains the individually distinct letter shapes of Comic Sans while looking slightly more polished.

These fonts share a common design philosophy: making each letter as visually distinct as possible, so that similar-looking letters like b, d, p, and q are harder to confuse. It's an intuitive approach. But does it actually work?

What the research actually says

This is where it gets interesting. Multiple peer-reviewed studies have tested these fonts with dyslexic readers, and the results are surprisingly consistent: specialised dyslexia fonts do not significantly improve reading performance.

Rello & Baeza-Yates (2013) conducted one of the most comprehensive studies, testing 12 different fonts with 48 dyslexic participants. They measured both reading time and accuracy. OpenDyslexic showed no significant improvement on either measure. The best-performing fonts were Helvetica, Courier, Arial, and Verdana — all standard fonts that ship with every operating system. The key finding was that sans serif fonts and larger sizes helped, not the specific design features that make dyslexia fonts different.

Wery & Diliberto (2017) studied the effect of OpenDyslexic on reading rate, accuracy, and error types among students with dyslexia. They found no statistically significant improvement in any measure. Perhaps more tellingly, none of the participants preferred OpenDyslexic when given the choice — they opted for the standard font they were already familiar with.

Kuster et al. (2018) tested the Dyslexie font specifically, comparing it against Arial. They found that Dyslexie did not benefit reading speed, accuracy, or comprehension. The majority of participants actually preferred Arial. The researchers concluded that the claims made about the font “were not supported by the evidence.”

These are not isolated findings. The pattern across the research literature is remarkably consistent: when tested rigorously, specialised dyslexia fonts perform no better than well-chosen standard fonts. This doesn't mean they're harmful — but it does mean the marketing claims outstrip the evidence.

Why these fonts might not help as much as claimed

The design features of dyslexia fonts — weighted bottoms, varied letter shapes, exaggerated ascenders and descenders — are based on assumptions about how dyslexia works that don't align well with current scientific understanding.

Dyslexia is primarily a phonological processing difficulty. It's about the connection between letters and sounds — the ability to segment, blend, and manipulate phonemes — not about letters looking similar to each other. The visual confusion theory (the idea that dyslexic readers constantly mix up b and d, or see letters “dancing on the page”) is largely a myth, or at least a significant oversimplification. Letter reversals are a normal part of early reading development and are not specific to dyslexia.

This matters because dyslexia fonts are designed to solve a visual problem, when the core difficulty is phonological. A font that makes b and d look more different doesn't help if the underlying challenge is mapping those letters to sounds.

There is, however, one design feature that does have evidence behind it: increased spacing between letters. Zorzi et al. (2012) found that wider letter spacing improved both reading speed and accuracy in dyslexic children. But this is something any standard font can achieve through formatting settings — it doesn't require a specialist font.

What the research does agree on

While the research is sceptical of specialist fonts, there is broad consensus on formatting features that genuinely help dyslexic readers. The good news is that these are all things you can do with any standard font:

• Sans serif fonts — Arial, Verdana, Calibri. Avoid serif fonts like Times New Roman or Garamond, which add visual clutter to letter shapes.
• Larger font sizes — 12–14pt as a minimum, with a willingness to go larger for pupils who need it.
• Increased letter and word spacing — this is the single formatting change with the strongest evidence base.
• Increased line spacing — 1.5 as a minimum, to prevent lines from visually merging.
• Avoiding italics — they distort letter shapes and reduce readability. Use bold for emphasis instead.
• Avoiding all-capitals — block capitals remove the ascender and descender cues that help readers recognise words by their overall shape.
• Left alignment, not justified — justified text creates uneven spacing between words, which is particularly problematic for readers who already struggle with tracking.

The message from the research is clear: the properties of the font matter far more than the name of the font. A well-formatted document in Arial at 14pt with generous spacing will outperform a document in OpenDyslexic with default formatting every time.

The BDA's position

The British Dyslexia Association's Style Guide is the most widely referenced accessibility standard in UK education, and its position on fonts is instructive. The BDA recommends standard sans serif fonts: Arial, Comic Sans, Verdana, Tahoma, Century Gothic, Trebuchet, and Calibri.

The guide does mention OpenDyslexic as an option, but it lists it alongside these standard fonts — not above them. There is no special endorsement, no suggestion that specialist fonts are superior. The BDA's emphasis is firmly on formatting properties: font size, spacing, background colour, and alignment.

This is significant. The UK's leading dyslexia charity — the organisation best placed to evaluate these fonts — does not endorse specialised dyslexia fonts over standard alternatives. Their guidance aligns with the research: get the formatting right, and the specific font matters far less than you might think.

A note on Comic Sans

Comic Sans is one of the most ridiculed fonts in design circles, but it is genuinely recommended by the BDA — and for good reason. Its letters are individually distinct: the lowercase a looks like a handwritten a, not a typographic one. It has natural spacing variation, and it was originally designed to be approachable and easy to read.

Research hasn't shown Comic Sans to be better than other sans serif fonts for dyslexic readers, but it's a perfectly valid choice. Teachers shouldn't feel embarrassed about using it. If a pupil reads more comfortably in Comic Sans, that matters more than any aesthetic objection. The font's poor reputation in graphic design has nothing to do with its readability.

Practical recommendations

So where does this leave you as a teacher? Here's what the evidence supports:

• Don't spend money on specialist dyslexia fonts. The evidence doesn't support their superiority over standard sans serif fonts. Your budget is better spent elsewhere.
• Do use a standard sans serif font at 12–14pt minimum. Arial, Verdana, Calibri, or Comic Sans are all excellent choices.
• Do increase letter and line spacing. This is the single most evidence-backed formatting intervention for dyslexic readers.
• Do avoid italics, block capitals, and justified text. These formatting choices create unnecessary barriers.
• If a pupil has tried a specialist font and reports that it helps them, there's no harm in continuing. The placebo effect is real, and reading confidence matters enormously. A pupil who believes a font helps them will approach reading with less anxiety — and reduced anxiety genuinely improves reading performance. But don't assume all dyslexic pupils need a special font.
• Focus your energy on formatting properties rather than font names. Spacing, size, colour, alignment — this is where the evidence is strongest, and these changes benefit every reader in your class, not just those with dyslexia.

The honest conclusion is this: specialised dyslexia fonts are a well-intentioned idea that the evidence hasn't validated. That doesn't mean formatting doesn't matter — it matters enormously. It just means that the right answer is simpler and cheaper than a specialist font. A standard sans serif font, properly sized and spaced, on a non-white background, with left alignment and no italics, will serve your dyslexic pupils well. The BDA Style Guide has the full details on getting these properties right.

The challenge, of course, is applying these formatting properties consistently when different pupils need different settings. One pupil reads best in Arial at 14pt with extra spacing; another prefers Comic Sans on a cream background; a third needs Century Gothic with wider word spacing. Doing this manually for every worksheet, for every lesson, is where the workload becomes unsustainable. That's why Adaptify stores each pupil's preferred font, size, spacing, and background colour as part of their profile — and applies them automatically every time you generate a resource.