2020-38 - Resize text testing methodology with formal example

From: @bsouster, July 15, 2020


What I’ve found is that while the WCAG guidelines do not state resize of font ONLY, the guidelines are considered to be technology-agnostic and there are requirements of font only resize on Desktop applications and software.

It came to my attention that people use the resize font settings in the operating system. I activated Windows 10 font size to 200%; this is what happened…


Font size adjusted to Firefox’s UI, but NO change to web sites and web content

Mozilla Firefox with Windows 10 font size activated to 200%


Font size adjusted to Chrome UI, and web sites and content set to 200% zoom as the default (100%). See screenshot below.

Google Chrome interface with Windows 10 font size activated to 200%

Internet Explorer 11

Same as Firefox (adjusts IE UI, but not web content)


I believe this is still a valid interpretation for Web sites and apps, since they do not state whether zoom suffices as text resize and OS text resize does not negatively affect web sites that pass 1.4.10 – Reflow (AA):

“When only one testing methodology is used, it must be browser zoom up to 400%, simultaneously passing Success Criteria 1.4.4 – Resize Text (AA) and 1.4.10 – Reflow (AA).”

I recommend we state that desktop applications and software require compliance to 1.4.4 – Resize Text (AA).