AI Alt Text
Generator

Understanding WCAG Alt Text Requirements

Alt text is the cornerstone of web accessibility for images. WCAG 2.1 Success Criterion 1.1.1 (Non-text Content) — a Level A requirement — mandates that all non-text content presented to the user has a text alternative that serves the equivalent purpose. This is one of the most fundamental WCAG criteria and one of the most frequently violated. The 2024 WebAIM Million report found that 54.5% of home pages had images with missing alternative text.

For blind and visually impaired users who navigate the web with screen readers like JAWS, NVDA, or VoiceOver, alt text is the only way to understand image content. Without it, screen readers either skip the image entirely (if the alt attribute is missing) or read the filename — which is often meaningless gibberish like "IMG_20240315_092347.jpg".

The Different Types of Images

Not all images need the same kind of alt text. WCAG recognizes several categories, each with different requirements:

• Informative images — convey information not available in surrounding text. These need alt text that describes the content (e.g., a product photo, a chart, a diagram).
• Functional images — used as links or buttons. Alt text should describe the function, not the image itself (e.g., "Search" for a magnifying glass icon button).
• Decorative images — exist purely for visual design and don't add information. These should use alt="" (empty alt) so screen readers skip them entirely.
• Complex images — charts, graphs, and infographics that contain substantial data. These need a brief alt text plus a longer description via aria-describedby or a visible data table.
• Images of text — should be avoided when possible (WCAG 1.4.5), but when used, the alt text must contain the same text shown in the image.

Writing Effective Alt Text: Best Practices

The goal of alt text is to provide equivalent information — not to describe every visual detail. Think about what a sighted user gains from the image, and convey that same information in text. Here are the key principles:

Be concise. Most screen reader users prefer brief alt text. A good rule of thumb is 125 characters or fewer. Some older screen readers truncate at this length, and even modern ones benefit from brevity. If an image needs more than a sentence of description, use a separate long description mechanism.

Don't start with "Image of" or "Photo of." Screen readers already announce the element as "image" or "graphic," so adding these phrases is redundant and wastes the user's time. Jump straight into the content.

Focus on content, not aesthetics. "A man wearing a blue shirt" is usually less useful than "CEO John Smith presenting Q3 earnings." Context matters more than visual details. What role does this image play on the page?

Include visible text. If an image contains text — a banner, a screenshot, a meme — include that text in the alt attribute. Users who can't see the image need to know what it says.

When to Use Empty Alt Text

The empty alt attribute (alt="") is not a shortcut or a lazy approach — it's a deliberate accessibility decision. It tells assistive technology that the image is decorative and should be ignored. Use it for:

• Background patterns, textures, and visual flourishes
• Spacer images or layout elements
• Icons that accompany text labels (the text already provides the information)
• Purely aesthetic photography that doesn't add information to the content

Critically, an empty alt attribute is different from a missing alt attribute. Missing alt is a WCAG violation. Empty alt="" is a valid, intentional accessibility choice.

Legal Requirements for Alt Text

Missing alt text isn't just a usability problem — it's a legal risk. Under the Americans with Disabilities Act (ADA), the European Accessibility Act (EAA), and Section 508 of the Rehabilitation Act, websites must be accessible to people with disabilities. Alt text violations are among the most commonly cited issues in ADA website accessibility lawsuits, which exceeded 4,000 federal filings in 2024. Ensuring all images have proper alt text is one of the most impactful — and straightforward — accessibility improvements you can make.

Beyond Single Images: Auditing Your Whole Site

This generator helps you craft alt text for individual images, but most websites have hundreds or thousands of images. Manual review doesn't scale. Automated accessibility scanners like RatedWithAI can crawl your entire site, identify every image with missing, empty, or suspicious alt text, and help you prioritize fixes. Combining AI-generated alt text with automated auditing gives you comprehensive coverage across your whole site.