ACT Rule b4f0c3
Meta viewport allows for zoom
A meta viewport tag carrying user-scalable=no, or a maximum-scale under 2, tells a phone browser to refuse pinch zoom. This rule finds that tag.
A tool can decide this one on its own, which is why it turns up in scanner output. The rule is approved, which in W3C's process means it was implemented in full by at least one tool or methodology and then signed off by a working group. Approval is a statement about tools, not a statement that this is the settled way to test the criterion.
What passing this rule proves
When this rule fails, 1.4.4 Resize Text is not satisfied, and that half is certain. When it passes, W3C's own outcome mapping says the criterion still needs further testing. So a green result here is evidence that one specific thing is not broken, and it is the answer W3C gives on 59 of its 87 live rules.
Most modern browsers now ignore the tag, and W3C says so on the rule page, so the rule matters mainly for older mobile browsers. The criterion is about whether text can reach 200% without losing content or function, which has to be tried rather than parsed. W3C lists 1.4.10 Reflow here as related rather than tested, so this rule does not decide it.
The criteria this rule is a test for
These are the criteria the rule names as its own conformance requirement. Each one is a far bigger question than this rule asks, and our page for it sets out what the whole criterion covers.
- 1.4.4 Resize Text Level AA
Criteria that are related but not tested here
W3C calls these secondary requirements. The rule correlates with them and was not designed to test them, so each one is either stricter than the rule or can be satisfied in ways the rule never looks at.
- 1.4.10 Reflow Level AA
The normative rule text lives at W3C
What the rule applies to, and exactly what it expects, is published by W3C and can change. We link to it rather than restate it, so nothing here can quietly fall out of date against the source. Read rule b4f0c3 at W3C.
Zoom must not be disabled
Magnifying a page is the most common accommodation there is. Plenty of people with low vision rely on it and use nothing else.
A viewport meta tag can switch that off. It was a common way to make mobile layouts hold their shape. It takes zoom away from everyone who needs it.
user-scalable=no or a maximum-scale set low disables zoom. Usually copied in from an old template without anyone noticing what it does. Users cannot magnify the page.
Fixes that satisfy it
If this rule fails on your site, these are the techniques that put it right.
Other rules W3C files under the same criteria
Each of these asks a different question about the same part of the standard. Passing all of them is still not the same as satisfying the criterion.
- Zoomed text node is not clipped with CSS overflow A tool finds candidates, you decide
All 87 ACT rules are grouped by the criteria they test, and 24 of them decide nothing about WCAG on their own. Run a free scan to see which of these your own pages trip.