Blog · Typography
Roboto, Inter, and system fonts for dyslexic readers
You probably read Roboto every day without knowing it. Google uses it across Search, Gmail, and Android. Inter is the house font of GitHub, Figma, Linear, and hundreds of modern web apps. The "system font stack" — San Francisco on Mac, Segoe UI on Windows — shows up anywhere a developer didn't bother specifying a typeface at all. These three fonts cover an enormous share of the text you encounter online. But none of them was designed with dyslexia in mind. How well do they actually hold up for readers who find text-heavy screens exhausting?
This article looks at each font through a practical lens: what were they designed to optimise for, where do they create problems for dyslexic readers, and what are the realistic alternatives you can apply right now.
Why "good" general-purpose fonts can still be hard for dyslexic readers
Roboto, Inter, and the system fonts are all genuinely well-made typefaces. They're legible at small sizes on screens, they render crisply on high-DPI displays, and they've been refined over years of real-world use. The problem is that "legible for most people" and "accessible for dyslexic readers" pull in different directions on a few key design decisions.
The three areas that matter most for dyslexic readers are:
Letter disambiguation. Certain letterform pairs cause disproportionate confusion — most famously b/d and p/q, but also I (capital i), l (lowercase L), and 1 (the digit). A font that draws these characters nearly identically forces dyslexic readers to work out meaning from context rather than from the letter shape itself. Many professional sans-serif fonts make this trade-off deliberately: a homogeneous style feels more refined and "modern," even at the cost of some distinctiveness.
Stroke uniformity. Fonts with uniform stroke weight — every part of every letter drawn at the same thickness — can make the page feel visually "flat." For some dyslexic readers this makes it harder to pick out individual characters from a block of text. Fonts with slight stroke variation, or that have heavier letter terminals, give the eye more to latch onto.
Spacing assumptions. Default letter-spacing and line-height are set for average readers at typical screen sizes. Research consistently shows that dyslexic readers benefit from wider letter-spacing and more generous line-height than most fonts ship with by default. This is fixable in CSS, but only if you control the site — which you usually don't.
Roboto — Google's workhorse
Roboto was created by Christian Robertson and released by Google in 2011 as the system font for Android. It's engineered for clarity at small sizes on lower-resolution displays, and it does that job extremely well. At body-text sizes on modern screens it's clean and neutral.
Where Roboto struggles for dyslexic readers:
The capital I has no serifs — it's a plain vertical stroke — and the lowercase l is nearly identical. On sites that use Roboto at small sizes (many mobile interfaces), I/l/1 become very hard to distinguish without context. The b and d are clearly differentiated by their bowl direction, but they share exactly the same stroke weight, which means some readers still report confusion.
Roboto also has relatively tight default letter-spacing at body sizes. Google's design guidelines recommend adding a small amount of letter-spacing for better readability, but most sites using Roboto don't follow that recommendation.
The honest verdict: Roboto is fine for readers who don't have significant letter-confusion issues. For readers who do, it's probably one of the harder common fonts to use, primarily because of the I/l/1 problem and tight default spacing.
Inter — the developer favourite
Inter was designed by Rasmus Andersson, released in 2017, and has become one of the most widely used interface fonts on the web. It was explicitly built for readability on screens at medium-to-small sizes, with a tall x-height (the height of lowercase letters relative to capitals) and open apertures (the openings in letters like c, e, and a).
Inter's tall x-height is genuinely useful for dyslexic readers. Research into x-height and dyslexia suggests that fonts with taller lowercase letters are easier to read because there's more visual information in each letter shape, reducing the chance of misidentification. Inter scores well here.
The letter disambiguation problem, however, is essentially the same as Roboto. Inter's capital I is a plain vertical stroke with no serifs, making it indistinguishable from the lowercase l in most rendering contexts. Inter does have a version with "stylistic alternates" that add serifs to the I and a curled tail to the lowercase l — this is available via the OpenType feature ss01 — but almost no website enables it by default.
Inter's default letter-spacing is slightly more generous than Roboto's, which helps, and the open apertures make characters like a, e, and c easier to distinguish from each other than in more closed designs. Among standard web fonts, Inter probably sits at the better end of the spectrum for dyslexic readers — but it still wasn't designed with dyslexia in mind.
System fonts — what you get by default
When a website specifies font-family: system-ui or a system font stack, you get whatever your operating system defaults to: San Francisco (SF Pro) on macOS and iOS, Segoe UI on Windows, and Roboto on Android (which loops back to the above).
San Francisco (macOS/iOS) has the best disambiguation of the three system fonts. Apple's designers added a subtle serif to the capital I and a curved tail to the lowercase l — changes that are invisible to most readers but make a real difference to anyone who relies on character shape rather than context to identify letters. If you're a Mac user, the system font stack actually works reasonably well for dyslexia.
Segoe UI (Windows) is closer to Inter in behaviour — clean, competent, but without the disambiguation features. The plain-stroke I is the familiar weak point.
The other weakness of system fonts is that you have no control over them. If a site uses system-ui and your system font is Roboto (as it is on most Android phones), you're stuck with Roboto on every site that didn't specify anything else. This is one of the stronger arguments for using a font-override extension.
How these fonts compare on the things that matter for dyslexia
| Roboto | Inter | SF Pro (Mac) | Segoe UI (Win) | |
|---|---|---|---|---|
| I / l / 1 disambiguation | Poor | Poor (default); Good with ss01 | Good | Fair |
| b / d / p / q clarity | Fair | Fair | Fair | Fair |
| x-height | Medium | Tall | Tall | Medium-tall |
| Aperture openness | Medium | Open | Open | Medium |
| Default letter-spacing | Tight | Moderate | Moderate | Moderate |
| Designed for dyslexia | No | No | No | No |
None of them scores well on the one column that matters most: none was designed with dyslexia as a use case. They're all optimised for the median reader at typical interface sizes, and the median reader doesn't have significant letter-confusion issues.
What actually works better — and how to apply it
The fonts that outperform Roboto, Inter, and system-ui for dyslexic readers share a few consistent traits: taller x-heights, wider default letter-spacing, open apertures, and deliberate disambiguation of confusable characters.
The main candidates are:
Atkinson Hyperlegible — designed by the Braille Institute specifically for low-vision and dyslexic readers. Every easily confused letterform was redesigned from scratch. The I/l/1 problem is solved definitively. It's available free from Google Fonts and works well at body sizes. Read more in our article on Atkinson Hyperlegible in Chrome.
Lexend — designed by Thomas Jockin following research on reading proficiency. It ships with wider letter-spacing baked in and was validated against controlled reading tasks. Lexend in the browser is a direct upgrade for readers who find Inter too tight.
OpenDyslexic — the most visually distinctive option, with weighted-bottom letter shapes designed to prevent mental rotation of b/d/p/q. Some readers find it too different from conventional type; others find it immediately easier. See our full OpenDyslexic guide.
The challenge is that you can't install these fonts on the websites you visit — only on sites you control. For everywhere else, a browser extension that overrides the site's font choice is the practical solution. LexiFont does exactly this: it replaces whatever font a site is using — Roboto, Inter, system-ui, or anything else — with whichever of the above fonts you've chosen. The substitution happens before the page renders, so you don't see a flash of the original font.
A quick test: if you're reading this article and find the font comfortable, that's Atkinson Hyperlegible — which LexiFont uses on this site. Now open Gmail (Roboto) and compare how the same length of text feels. If there's a noticeable difference in fatigue or reading effort, that's a signal that font choice is doing real work for you.
Can you fix these fonts without switching them?
If you work somewhere that mandates Roboto or Inter — in a design system, for example — there are partial mitigations:
Letter-spacing. Adding letter-spacing: 0.03em to body text in Inter or Roboto noticeably reduces crowding. Research on letter-spacing and dyslexia consistently shows that a small increase — around 3-5% of the em — improves reading speed for dyslexic readers without disrupting layout significantly for others.
Line-height. Both Inter and Roboto ship with a default line-height of around 1.2-1.3 in many implementations. Bumping this to 1.5-1.6 gives the eye a clearer path from one line to the next and reduces the chance of landing on the wrong line — a common problem described in our article on dyslexia and eye tracking.
Inter's stylistic alternates. If your site uses Inter and you control the CSS, adding font-feature-settings: 'ss01' 1, 'cv05' 1 enables the disambiguated I/l forms and a more distinct numeral 1. This single change resolves the biggest legibility complaint about Inter at essentially no cost.
Font weight. Roboto and Inter both have a Medium (500) weight that many dyslexic readers find easier than Regular (400) without the heaviness of Bold. Our article on font weight and dyslexia covers this in detail.
These adjustments help, but they only fix what you can reach. For the rest of the web — Gmail, GitHub, Reddit, every news site using system-ui — you need a tool that works at the browser level.
The bigger picture: why this matters on most websites
Design systems at large companies are conservative. Google chose Roboto in 2011 and it's effectively locked in across hundreds of products. GitHub adopted Inter across its interface in 2023. These decisions reflect the needs of the median user, where "needs" means not making font choice a distraction — not optimising for the roughly 10-15% of users who have dyslexia.
This isn't a criticism of those decisions. Roboto and Inter are genuinely good fonts for their intended purpose. The problem is that their intended purpose was "works well for most people," and dyslexic readers don't fall neatly inside "most people" when it comes to letter disambiguation and default spacing.
The practical upshot: if you have dyslexia and spend significant time on Google products, GitHub, or any site using a system font stack, you're spending that time reading text that was never designed for you. That cumulative friction — the extra effort of working out I from l, of tracking across tightly spaced lines — adds up over a workday. Changing the font doesn't require convincing Google or GitHub to update their design systems. It just requires overriding their stylesheet in your browser.