So we have decided to make our website more accessible and I'm studying the WCAG recommendations right now. I can clearly see that there is a difference between Level A, Level AA and Level AAA. It's also clear that if I go for the Level AAA the site will be accessible to more people.

But, it's more expensive if we try to reach the highest level. I haven't found how many more people we could reach by aiming at the level. That number could motivate a higher development and maintenance cost.

–So, how many more people in general do I reach if I go for Level AAA instead of Level AA or Level A?

  • This depends entirely on your audience. As some answers cite AAA is most situations is overkill. To put it into context I design self service web apps for local government and they only require AA. – Wander Mar 23 '15 at 16:06
  • Yes, I know. Our target audience is very broad so thats why I want to start with general numbers. – Tony Bolero Mar 24 '15 at 12:52
  • Also the W3C, understanding WCAG 2.0, states, 'Note 2: It is not recommended that Level AAA conformance be required as a general policy for entire sites because it is not possible to satisfy all Level AAA Success Criteria for some content'. – Neil Apr 2 '17 at 12:40

Tricky question. I wouldn't really think of it in terms of percentage / number though, but more of a general target audience. Who is the target audience of the site? What sort of website is it? In most cases, aiming for AAA is overkill and (dare I say it) unnecessary. The majority of the AAA criteria relates to multimedia content and being able to serve that content to all possible users. A primarily text-based site (news site, ecommerce etc) is pretty much accessible to most people, provided it is built properly and to correct web standards.

AAA is a huge maintenance overhead rather than a development one (transcribing all videos, filming sign-language versions, providing alternative versions of all image based content...) so you can likely still build a site to be AAA compliant to start with, with the onus on the content managers to keep it AAA.

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    I disagree that AAA is overkill. It is completely subjective to what you are producing. Lynda.com for example... it is not overkill, it is certainly a necessary thing if they want to reach all of their users. Craigslist? Maybe not so much. It completely depends upon the situation. – AzKai Mar 20 '15 at 16:50
  • @AxKai I think adhering to published guidelines can be overkill. I find that that is often a distraction from bigger-picture accessibility goals. I've been on a lot of teams that produce WCAG compliant code, but still produce rather inaccessible sites--as they miss the entire spirit of the guidelines. – DA01 Mar 20 '15 at 17:28
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    This is a good answer; you must consider the content and the audience. The WCAG authors actually make the point that Level AAA conformance should not be adopted as a general policy for entire sites because it is not always possible to meet all of the AAA guidelines. – Matt Obee Mar 20 '15 at 17:41
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    @Izhaki I didn't say AAA is overkill. I said that it is overkill in most cases. Being accessible itself is not overkill, it is just the way things should be. AAA is a step up from that and usually only beneficial depending on the type of site. And it takes a huge commitment from that content administrators to keep it that way. – JonW Mar 20 '15 at 17:48
  • @DA01 I'm not speaking necessarily of published guidelines. What each project needs is different. You need to decide what your users need, then develop that. Don't waste time on what won't help them. JonW I don't see ADA in terms of A, AA and AAA. I see it in terms of: Can a disabled person actually use this? A, AA and AAA really is: "Does this ADA tool say you passed the guidelines"? And that doesn't tell you if someone can effectively use your site or not. The A, AA and AAA I believe were made because it is the law for government sites to be "compliant", so they had to make those rulesets – AzKai Mar 23 '15 at 14:05


Your question can't be answered unless you know your audience. This means you need the actual data from your users. Of course, I'm not just going to say that without giving you some type of estimate--but you should know this is highly inaccurate compared to actual statistics for your website.

Global Statistics


If we want to guestimate, though... (cringe) then you have to think of a few different scenarios. If your website is a world-wide site, then you should know that 39 million people are completely blind in the world, and 285 million people are visually impaired in some way. If you are looking at just North America, then to my knowledge at least 1.3 million Americans are legally blind--which was roughly .3% of the population in 2010. Not all 1.3 Million people will be using your site; however, so if you want even more detailed statistics... well, you see where I am going.


When people think ADA they mostly think Blindness, but Deafness is just as important. There was a study in 2002 which stated approximately 1 million Americans were functionally deaf. This means subtitles, closed captions, etc would be very important for any videos or audio you might have on your site.

Other Disabilities

I would love to go on about Dyslexia, Color Blindness, etc but those are not necessarily covered by ADA Guidelines--they are basic UX practices--and your question doesn't ask about those... (Cry) (10%~ of people in the world are color "blind" (deficient), and as much as 15% of Americans have Dyslexia.)

ADA Considerations

If your website is a government-owned site, than being being 508 Compliant is actually a legal issue. If your website is not ADA Compliant, you could be sued.

The Numbers

Anyway, it could be safe to assume that on a very, very loose scale your site could perhaps have .05% - .2% of visually or auditory impaired users. (Note: As I mentioned before, this is a loose statistic I calculated guessing on the Asker's user base and the average of Americans with disabilities. Also, I'm bad at math.)

There are many more impairments that effect users, so other impairments could total from 5% - 20%. (But only half of these will likely be included in ADA Findings, the others are mere UX-Best-Practices.)

Questions to ask yourself

Will you make an ROI if you make your website more accessible? For instance, eCommerce sites will lose out on a small percentage of sales if disabled or impaired users cannot use their site.

Do you have a UX Designer / Front-End Developer / Web Designer, or are developers doing the front-end coding? Back-End Developers usually have a basic knowledge of HTML but advanced knowledge of HTML is required to be completely ADA Compliant--meaning you'll need a Front-End Developer. If Back-End Developers try to do the development, you'll spend more time and money developing for ADA.

My Professional Recommendations

If you're not sure you're ready to spend the extra time, money, effort and headaches to make everything in your site / software accessible, I would suggest starting small. Make sure all CTAs are ADA Compliant and can be reached via screen reader, users using the TAB key, etc. Anything very important to your site--like navigation--make that compliant.

You could then use A/B testing with the non-ADA compliant site with the new ADA-compliant site, and see if you get more traffic to pages, more clicks on the CTA, etc.

Also, crunch your user numbers. Google Analytics is really easy to set up and can help a lot with figuring out your users. For more advanced information, you can set up a survey on your site with optional information they can submit to you to help you make the site more accessible.


Added references. Also, someone mentioned the user is asking about WCAG and not ADA / Section 508 compliance. So, here's my answer to that.

WCAG, Section 508 & ADA--oh my!

Section 508 defines the minimum level of web standards which, by law, must be developed by any government agency using the web as a means of communication. WCAG actually came first, and these were a set of recommended guidelines which became official in 1999. Since then, these two sets of guides have worked in tandem to help businesses touch everyone--no matter their disability.

Yes, the user is asking about WCAG which is where the three stage guides come into play. However; as I mentioned above, those guides will not dictate how well the application actually works for an impaired user. The only way to tell this is by using the software yourself as if you have that impairment which you are testing.

I hope my answer touches on enough of all of these differently labeled but very similar guidelines, so that the Asker can make the best choice for his/her business.


1 http://www.who.int/mediacentre/factsheets/fs282/en/

2 https://nfb.org/fact-sheet-blindness-and-low-vision

3 http://www.cdc.gov/ncbddd/hearingloss/data.html (Note: I got the original estimate somewhere else, but found this reference to be more informative.)

4 http://www.colourblindawareness.org/ (Note: 8% of males and 1% of females. I added these then rounded up for buffer.)

5 http://www.dyslexia-add.org/

6 http://www.section508.gov/summary-section508-standards

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    Not a bad answer, but you are referring to ADA, while the question is referring to WCAG. – DA01 Mar 20 '15 at 17:26
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    This is a really good answer, but it really needs some citations from where you get your figures from. I'm not disagreeing with you but it is just more appropriate if you are citing statistics that you cite the sources as well. – JonW Mar 20 '15 at 17:52

"But, it's more expensive if we try to reach the highest level"

It shouldn't be. If it is, it likely means you're doing a whole lot of retrofitting of poor content and markup. Remodeling a house that is falling down is always more expensive than building a new solid one from the start.

Keep in mind that WCAG specs are guidelines. Not magical levels where you instantly suddenly get a larger audience. So don't put to much weight into the specific details, but rather put your weight into the overall spirit of the guidelines.

In the end, it's impossible to say how many more people you will reach if you meet each level. I think we can confidently say you have the potential to reach more people than if you don't meet the guidelines, but specifics would depend entirely on your user base.

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    Unfortunately it is more expensive to have a AAA site. Putting a video on the site? Then you need a sign language version, an audio description version, a textual transcription and a textual descriptive version, and need to be able to offer these to whomever wants them. That is a massive overhead, however you look at it. – JonW Mar 20 '15 at 17:58
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    @JonW fair point. "Being accessible" shouldn't cost more. Meeting particular guidelines may very well be more accessible--which is yet another reason I'd argue to not put to much weight on the specifics of the guidelines, but aim for the spirit of them. At the end of the day, a person doesn't care that you meet some standard. All that they care is that they can use your site. – DA01 Mar 20 '15 at 18:01
  • Like @JonW said. You end up paying more money for these extra items to be done in most circumstances. Sometimes, it may even result in having to hire a consulting company. That being said to your original point, yes, a seasoned Front-End Developer should be implementing basic HTML for accessibility anyway, which should not increase costs by a noticeable amount. – AzKai Mar 23 '15 at 14:37

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