Links/buttons to adjust font size used to be one of the accessibility must-do's but do we still need to include the text scaling links on our sites?

Most modern browsers and operating systems support page zooming or text sizing. Are buttons to control text size overriding or conflicting with those features?


8 Answers 8


Before attending the Standards.Next event on Cognition and Accessibility, I would have agreed with Nathanael and Andrew, but listening to two of the speakers who had recently done usability testing effectively changed my mind.

In her presentation on Accessibility beyond code, Antonia Hyde presented video footage of some very interesting usability tests. One of her conclusions was that "Alternative ways to access content like text size or colour scheme can make or break a site."

In Cognitive accessibility testing, David Owens came to a similar conclusion. I think it's worth quoting him at length because he directly addressed my point of view up to that point.

The next thing which I want to talk about is related, in that it is also an example of idealism, or dogma, versus pragmatism. For a long time I had taken the view that educating people about how to use their browser was the best way to make the web more accessible. A key example of this is text-resize widgets.

I was sat down with Richard, who has a mild learning difficulty, and I asked him if there was anything he could think of that would make it easier to use the website.

The first thing he said was "I wish there was a way to make the text bigger".

I replied, "Well you can do that the same way you do it for any website", knowing that all our fonts were set up nicely, and that we had zoomed in on every page we built at the design stage.

Richard explained that he had been told how to do that lots of times before, but that it was difficult to remember. There were so many menus and short cuts to learn that he had simply given up trying.

When put that simply, the case for presenting that option up-front seems pretty solid. Of course there are all kinds of browser settings that could, or should, be easier to get at, but for something as simple as a text-resizer it seems a no-brainer.


I think it's important to remember why text scaling links exist and what they 'teach' users. Text scaling was, until relatively recently, a problem for some browsers depending on how you specified your font-sizing and were a very necessary part of the interface to help users around this.

However, they are weak as a general UI convention because:

  • they are rarely applied/positioned consistently
  • they provided limited 'choice' in adjusting text size
  • they don't help users understand how to best make use of the tools available within their browser to the benefit of accessibility more generally, rather than the website they are currently on

So, if you have to have them, I'd suggest providing supplementary information about how to scale text / page zoom using the browser's built in features too as part of an accessibility page.

  • I couldn't put it any better.
    – Philip Morton
    Commented Jan 26, 2010 at 11:42

From my expirience I said yes. Beacause today the browser don't work like a text scaling but like zoom. The difference? Scrolling of course, specially horizontal scrolling and people with low vision problem don't like horizontal scrolling (or have serious usability problem with this kind of scrolling)..

I can suggest you some articles.

  • Text scaling is a setting in Firefox, or a different menu action in IE. It's a pity that 'zoom' is the default for the very reason you give here.
    – Bobby Jack
    Commented Feb 12, 2010 at 14:41

I rarely have explicit "Font + / -" controls on the web UI; we did for AgedCareAustralia.gov.au due to the target audience but for the most part leave it up to in-browser font resize controls although as Elmook said, zoom is now taking over.

I almost always use relative measurements throughout my designs; non-zoom browsers can't handle fixed sizing px measurements but also it's easier to adjust your design, especially with inheritance etc. Just makes the design more adaptable, maintainable and extensible.

  • Nathaniel you make a great point - you used the controls where your audience - elderly folk would benefit from it, and might not be as technological aware as other user groups.
    – Nathan-W
    Commented May 17, 2010 at 3:37

We did several tests with people who do have a problem with reading small text size - they all knew how to adjust the text size/zoom level within their prefered browser - all of them. On the other hand it gave us some problems that some browsers (IE) store the zoom level on a global base and some (FF) do it for specific sites. The last option is what we are looking for and if we think about a solution that will work with all browsers: we need our own implementation and can not rely on the browser.

  • 1
    Are the results of those tests publicly accessible?
    – Bobby Jack
    Commented Feb 12, 2010 at 14:43

I think this really depends on a site's main audience. If our clients' main site visitors are older folks or less web savvy users, we'll include a font re-sizer. Not everyone knows they can resize the font themselves. For the most part though, we let the user control their own experience and uss CSS with relative font sizes.


Yes of course. Text scaling is very useful, adds nice usability to the site.

Medium experienced users always use "control+whellup/whelldown" to increase or decrease font size, specially when reading long texts.

So i personally think the best way is to use relative font sizes in "em".


Got to pondering this question a bit more and looked at what WCAG recommends

WCAG Sufficient Techniques for 1.4.4 - Resize text

WCAG doesn't prescribe the controls, but they aren't first on their list of sufficient techniques either.

Of particular interest though is the technique -- G179: Ensuring that there is no loss of content or functionality when the text resizes and text containers do not resize -- this is exactly what can happen with a...A zoom controls if they don't also modify the size of the containers or handle text wrapping correctly.

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