Missing Image Alt Attribute: How to Fix Informative Images
Direct Answer
A missing image alt attribute means an <img> element has no alt attribute at all. For an informative image, add concise alternative text that communicates the essential information or purpose. For a purely decorative image, use alt="" rather than omitting the attribute; an intentionally empty alt is a separate state.
Documentation
What this finding means
Site SEO Audit reports image_alt_missing when an image element has no alt attribute. This is different from alt="", which may be correct for a decorative image and is reviewed separately.
The fix therefore starts with the image's purpose, not with automatically generating text for every file.
Informative images need useful alternatives
W3C guidance says informative images should have a short text alternative that conveys their essential information. Google also uses alt text, together with page context and computer vision, to understand image subject matter.
Write what is important about the image in this page's context. A product photo may need the product and variant. A diagram may need the conclusion it communicates. A screenshot may need the interface state that matters to the surrounding instructions.
Decorative and functional images are different
If an image is purely decorative and adds no information, W3C recommends a null alternative: alt="". That allows assistive technology to ignore the decorative image.
If an image is a link or button, describe its function or destination, not merely its appearance. Google can also use image alt text as anchor text when the image is inside a link.
Avoid keyword stuffing and filename descriptions
Alt text should not be a list of target keywords. Google explicitly warns against filling alt attributes with keywords.
Also avoid mechanically turning filenames into alt text. IMG_1038.jpg says nothing useful, and even a descriptive filename may not capture the image's purpose on this page.
Verify the fix
Review each image reported by the audit. Add meaningful alt text to informative images and alt="" to genuinely decorative images. Check linked images for destination-oriented text.
Re-run the audit and confirm image_alt_missing is resolved. Empty-alt findings may remain for decorative images and should be judged separately rather than “fixed” automatically.
Questions & Answers
Is alt="" the same as a missing alt attribute?
No. A missing attribute provides no explicit alternative-text decision. alt="" intentionally marks an image as having a null text alternative and is often correct for decorative images.
Should every image have descriptive alt text?
No. Informative images need a useful alternative. Purely decorative images generally use alt="", while functional images should describe the action or destination.
Does alt text need SEO keywords?
Use relevant words only when they naturally describe the image. Do not insert keyword lists. Google warns that keyword stuffing in alt text creates a poor experience and may look spammy.
How long should alt text be?
There is no single SEO character target. Keep it as concise as possible while preserving the essential information or function. Complex information may need a longer description in page content.
Practical Check
- Classify each reported image as informative, decorative, or functional.
- Add concise, contextual alt text to informative images.
- Use
alt=""for images that are genuinely decorative. - Describe the action or destination for linked or button images.
- Re-run the audit and confirm
image_alt_missingis gone.