How Accessibility Widens Your Total Addressable Market

Every pitch deck has a slide about total addressable market. Founders compute it by multiplying the number of people who might want the product by some price. The number is always large. What nobody puts on the slide is the silent assumption underneath it: that everyone in that market can actually operate the thing you built to sell to them. For a software company, the storefront is a website, and the assumption is that the website works for everyone. It usually doesn’t.

Think of your market not as one circle but as two. The outer circle is everyone who wants what you sell. The inner circle is everyone who wants it and can get through your site to buy it. The gap between the circles is invisible in your analytics, because the people in the gap don’t show up as failed conversions with helpful error events. They show up as nothing. A blind user whose screen reader announces your buy button as “button” doesn’t file a ticket. Someone with a tremor who can’t hit your tiny close icon on a modal doesn’t email support. They leave, and your dashboard records a bounce indistinguishable from someone who wandered in from the wrong search result.

The gap is bigger than intuition suggests, because intuition pictures disability as rare and binary. It is neither. Vision alone spans a whole range: blindness, low vision, color vision deficiency, and the ordinary farsightedness that arrives for nearly everyone past forty. Motor control spans arthritis, tremor, repetitive strain injuries, a broken wrist. Hearing matters the moment your product explains itself in videos. Cognition matters everywhere, and it’s the one founders think about least: dense paragraphs, ambiguous button labels, and forms that scold you in vague terms are barriers as real as any missing alt text. Then add situational impairment, which is disability’s temporary cousin. Sunlight is low vision. A crying baby in one arm is a motor impairment. A loud train is deafness. Design for the permanent case and you’ve handled the temporary ones for free.

Demographics push the same direction. Populations in most wealthy countries are aging, and aging is a gradual acquisition of exactly the impairments accessibility addresses. The customers with the most money are disproportionately the customers with declining eyesight and stiffer hands. A site optimized only for twenty-five-year-olds with perfect vision on flagship phones is optimized for the segment with the least disposable income.

Here’s what makes this a market question rather than a charity question: the excluded users are not marginal buyers. They want the product as much as anyone, sometimes more. Someone who can’t easily visit stores has a stronger reason to shop online, not a weaker one. When your site excludes them, they don’t stop buying. They buy from the competitor whose checkout they can finish. Accessibility failures don’t shrink demand; they redirect it. That’s the worst kind of loss, because you paid the marketing cost to attract the customer and then handed the revenue to someone else at the last step.

The economics of fixing this are unusual and favorable. Most ways of widening a market are expensive: new features, new geographies, new sales teams. Accessibility widens the market by removing defects from what you already built. Text alternatives on images, labels on inputs, sufficient contrast, keyboard operability, sensible heading structure. None of this is new product surface. It’s finishing the product surface you have. And unlike a feature bet, you don’t have to guess whether anyone wants it. The people in the gap already demonstrated demand by showing up.

I see this concretely in the scans GazeSite runs. The sites with the worst accessibility scores are almost never bad because the founders decided to exclude anyone. They’re bad because nobody ever looked. A div styled to look like a button but invisible to keyboards. A form that communicates errors only by turning a border red, which a colorblind user simply cannot see. Each one is a small hole in the inner circle, and the holes compound: a user who survives the unlabeled navigation still has to survive the inaccessible checkout.

So if you want a more honest TAM slide, run the correction yourself. Take the market you claim, and ask what fraction of it can complete your core flow with a keyboard, with a screen reader, with weak eyes, with one hand. You don’t need a study to know the answer isn’t all of it. The good news is that this is the rare market-expansion strategy where the customers are already at the door. You don’t have to find them. You just have to stop locking them out.