G142Sufficient technique WCAG 1.4.4 Level AA Partly scanner-detectable

Build with technologies whose browsers support zoom

G142 is a choice made early. Build in a technology whose common browsers can scale it, and text resizing mostly takes care of itself, because the browser does the work. W3C is careful about what counts. Zoom has to preserve the spatial relationships on the page and keep every function available, not merely make things bigger, and because the whole technique leans on the browser, W3C says test it across a wide range of them. This is a sufficient technique for 1.4.4 Resize Text at Level AA, whose threshold is 200 percent. Do not carry that number over to reflow, which is a separate rule with a 400 percent zoom equivalence. One practical blocker is not in the technique text. A viewport meta tag that disables user scaling switches this off on mobile, and that is our observation rather than W3C's.

How we find it in an audit

Our reviewers zoom to 200 percent in more than one browser and read the page. We look for text that stops growing, content that gets clipped by a fixed-height box, and controls that move out of reach. Embedded viewers and legacy plugins get checked on their own, since they often ignore browser zoom entirely.

How affected users experience it

Plenty of people with low vision never install a magnifier. They set a larger default in the browser and use zoom, which is why zoom that works is quietly one of the most-used accommodations on the web. When an embedded tool refuses to scale, they are left with the surrounding page at a comfortable size and the part they need at a size they cannot read.

Passes vs. fails

Passes: the button grows with its text. Fails: fixed sizes shear the label.

Passes

The same tools are standard HTML, so every mainstream browser zooms them to 200 percent with nothing clipped or lost.

Fails

Critical account tools are delivered through a legacy embedded viewer whose text does not scale when the browser zooms.

How this gets tested

The W3C publishes test rules that define what a checker looks for here.

Meta viewport allows for zoomA tool can check this
Zoomed text node is not clipped with CSS overflowA tool finds candidates, you decide

Other ways to satisfy this rule

15 guides on this site are filed under 1.4.4 Resize Text. W3C lists this one as sufficient for that rule on its own. Implement it correctly, in a way your readers' software actually supports, and the rule is met.

This guide is our interpretation of W3C technique G142: Using a technology that has commonly-available user agents that support zoom. W3C publishes its techniques as guidance rather than as the standard, and says so on every one of them. The success criterion is what conformance is measured against, and a technique is one documented way to meet it.