G92Sufficient technique WCAG 1.1.1 Level A Partly scanner-detectable

Write long descriptions carrying the same information

The short alt names the image. The long description carries what it says. G92 is about the second of those, and W3C counts it as sufficient for the non-text-content rule at Level A with no conditions attached. The test it sets is a strong one, and it is why this technique matters. Take the image off the page, put the short and long alternatives in its place, and the page should still do the same job and give the same information. Four questions get you there. Why is this here. What is it presenting. What purpose does it serve. And if the picture were gone, what words would carry the same function. For a chart, the answer is usually the numbers, and sometimes the answer is a table.

How we find it in an audit

A reviewer reads the description with the image hidden and asks whether the page still works. For a chart, the numbers have to be there. For a diagram, the relationships. For a photograph carrying an argument, whatever the photograph was arguing. Then they look at the image beside the words and list what a sighted reader takes away that the description never mentions, and that list is the finding. Descriptions summarizing the impression rather than the content are the common shape, and they read beautifully and fail.

How affected users experience it

A blind reader who reaches a long description is expecting the same thing everybody else got. When it arrives as a colorful bar chart showing quarterly sales, they get an impression instead of information, and nothing marks the difference. So they carry on with a confident understanding of something they were never actually told. That is worse than a missing description, because a missing one at least announces that something is missing.

Passes vs. fails

Passes: alt text names the product. Fails: the file name is all there is.

Passes

Sustainability 2025. Emissions down 22%. Water use down 9%. Renewables at 64% of supply. The six figures, written out in text.

Fails

Infographic about our sustainability progress, describing an image that carries six specific measurements.

How this gets tested

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

Element marked as decorative is not exposedA tool can check this
Image accessible name is descriptiveA tool finds candidates, you decide
Image button has non-empty accessible nameA tool can check this
Image has non-empty accessible nameA tool can check this
Link has non-empty accessible nameA tool can check this
Object element rendering non-text content has non-empty accessible nameA tool can check this
SVG element with explicit role has non-empty accessible nameA tool can check this
Image not in the accessibility tree is decorativeA tool can check this

Other ways to satisfy this rule

39 guides on this site are filed under 1.1.1 Non-text Content. 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 G92: Providing long description for non-text content that serves the same purpose and presents the same information. 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.