Rule library Text alternatives

Images must have alternative text

image-altWCAG 2.0 A

Ensure <img> elements have alternative text or a role of none or presentation

Who this affects

Screen readers announce these images as "image" or read the file name aloud. Customers using assistive technology cannot tell what is shown.

How to fix it

Add a descriptive alt attribute to every meaningful image. Decorative images should carry alt="" so they are skipped.

Effort Low · ~5 min per image

Before and after

Fails

<img src="/img/kettle-9013.jpg">

Passes

<img src="/img/kettle-9013.jpg"
     alt="Stainless steel kettle with a black handle">

<!-- purely decorative: -->
<img src="/img/swirl.svg" alt="">

Where this sits in the standard

WCAG success criterionLevelEN 301 549 clause
1.1.1 Non-text ContentA301-549, 9.1.1.1

EN 301 549 clause 9 applies these criteria to web content. The published version referenced by the European Accessibility Act is V3.2.1, which incorporates WCAG 2.1 level A and AA. More on the standard.

How to check it by hand

Turn images off in the browser, or run the page through a screen reader and listen to the image announcements. If you hear a file name, a hash, or nothing where something meaningful should be, the alternative is missing. Ask of every image: if this were removed, what would the reader need told?

Automated testing settles roughly a third of the WCAG success criteria. This rule is one an automated tool detects reliably — but a clean automated result is not proof of conformance.

Reference

Deque's technical write-up for this rule: image-alt

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