Image Alt Text: 10 Best Practices That Work in 2026

Write alt text that describes what the image actually shows. Do not force keywords into every description. Google's image best practices state that alt text should provide a clear description of the image content for users who cannot see it. An image of a red mountain bike should have alt text like "red mountain bike on a dirt trail," not "best bike for sale." https://developers.google.com/search/docs/appearance/google-images

Keywords belong in alt text when they fit the description naturally. A 2025 study by Ahrefs found that images with keyword-rich alt text appeared in Google Image Search results 43% more often than images with generic alt text. Do not stuff. If the image shows a chocolate cake, "chocolate cake with vanilla frosting" is effective. "Chocolate cake best dessert recipe buy now" is not. https://ahrefs.com/blog/image-seo/

Screen readers cut off alt text at around 125 characters. Keep descriptions concise. A W3C guideline recommends limiting alt text to a brief phrase or short sentence. If the image requires a longer description, use the longdesc attribute or describe it in the surrounding body text. https://www.w3.org/WAI/tutorials/images/

Screen readers already announce an element as an image. Repeating this is redundant. "Mountain summit at sunrise" is better than "Image of mountain summit at sunrise." Google also ignores redundant alt text patterns. Every word in the alt attribute should earn its place.

Buttons, icons, and logo links need descriptive alt text that tells users what the link does, not what the image looks like. A search magnifying glass icon should have alt="search" not alt="magnifying glass icon." Google uses link image alt text as anchor text for the linked page. https://developer.mozilla.org/en-US/docs/Web/Accessibility/ARIA/Roles/img_role

Images that add no informational value should have an empty alt attribute. Do not omit the attribute entirely. A null alt (alt="") tells screen readers to skip the image. Omitting the attribute causes some screen readers to read the file name. Decorative borders, background flourishes, and purely visual elements should all use alt="".

Ecommerce product images need alt text that includes the product name, color, size, and relevant attributes. Google Shopping uses alt text as a ranking signal. A product image alt text should read "Nike Air Max 270 black size 10 men running shoe" not just "shoe." Include the SKU or model number when relevant.

Run a sitewide crawl to find missing alt attributes, empty alt text on meaningful images, and keyword-stuffed alt text. Screaming Frog and Sitebulb both export alt text reports. A 2025 analysis by Semrush found that 38% of indexed images had missing or empty alt attributes. https://www.semrush.com/blog/image-seo/

When a caption below the image already describes the content, the alt text can be shorter or empty. The caption provides the context. Duplicating a long caption in alt text creates a poor experience for screen reader users who then hear the same text twice.

Run your pages through a screen reader like NVDA or VoiceOver. Listen to how your alt text sounds in context. Alt text that looks correct in the HTML source often sounds awkward when read aloud. Fix these issues before they affect user experience.

Export all images from your site crawl. Check for missing alt attributes, keyword stuffing, and alt text longer than 125 characters. Flag decorative images that lack alt="". Note the gap between your current alt text and these practices. Audit quarterly. Alt text degrades as content changes and new images get added without proper descriptions.