Re: Clarification for Zoom Requirements with WCAG SC 1.4.4 for Desktop and Mobile Devices

On 27/04/2026 22:29, Hash, Colton wrote:

> So to my understanding, a web page could pass SC 1.4.4 if it can scale 
> up to 200% with full-page zoom in a 1280px wide window, even if font- 
> only zoom up to 200% does not work?

 > *This suggests that accommodating font-only zoom is not necessary?*

Correct. These days, full-page zoom is by far the most common way of 
resizing text. To my knowledge, only Firefox and Safari still have a 
text-only zoom. In the case of Firefox, the option is exposed in the 
View menu (noting that on Windows, the traditional menu bar is hidden by 
default, and there's no equivalent function in Firefox's "hamburger" 
type menu) and in the Settings. In Safari, it appears that the option is 
completely hidden and only available via the (undocumented?) 
Option+Command+plus/minus keyboard shortcut (where regular 
Command+plus/minus is full-page zoom).

> For mobile devices, users also need to be able to increase font size by 
> 200% with device or browser settings. Scaling a 320px wide mobile device 
> viewport by 200% full-page zoom without scrolling would effectively mean 
> that all layouts would have to scale down to 160px wide?

Careful, browsers on mobile/tablet OSs don't change viewport size when 
zooming (instead, they use a secondary layout viewport that is set once 
the page is rendered, and pinch/zooming zooms into this layout viewport, 
so the page width/height do not change and instead you scroll 
horizontally/vertically ... and again, for the purposes of 1.4.4, this 
is fine).

 > Taken with SC 1.4.10, I assume that a mobile browser should not scroll
 > in 2 dimensions with browser scaling up to 200%, even though page
 > content is technically below the 320px wide threshold stated in SC 
1.4.10?

Once the user pinch-zooms and the browser itself causes horizontal and 
vertical scrolling, that's outside of the author's control, so 
irrelevant for 1.4.10.

-- 
Patrick H. Lauke

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Received on Monday, 27 April 2026 22:14:41 UTC