Missing Alt Text: Fix Image SEO and Accessibility Issues
Alt text is the written description assigned to an image via the alt attribute on an <img> tag. When it's missing, search engines cannot understand what the image shows, screen readers skip the image entirely for visually impaired users, and you lose potential Google Image Search traffic. Fixing missing alt text improves SEO, accessibility scores, and Core Web Vitals compliance simultaneously.
Why Alt Text Matters for SEO
Google's image recognition has improved dramatically, but text signals still heavily influence how images are indexed and ranked in Google Images. Alt text provides the clearest textual context for an image. Pages with properly described images rank more easily in image search results, which can drive significant referral traffic — especially for e-commerce, food, travel, and visual content niches. Alt text also contributes to the overall keyword relevance of the page for text-based search.
Accessibility: The Other Half of Alt Text
Screen readers used by blind and low-vision users read alt text aloud in place of the image. Without it, users hear "image" or the filename — neither is helpful. WCAG 2.1 guidelines require meaningful alt text for all informative images. Websites that fail accessibility requirements face legal risk under the ADA (USA), EN 301 549 (EU), and similar legislation in other regions. Fixing alt text is therefore both an SEO task and a legal compliance task for most organisations.
How to Write Good Alt Text
Good alt text describes the image accurately and concisely in under 125 characters. Write it as you would describe the image to someone who cannot see it. Include relevant keywords naturally when they genuinely describe the image — never force keywords where they do not belong. Avoid starting with "image of" or "photo of" since screen readers already announce it as an image. For product images, include the product name, colour, and key attribute: "Blue leather wallet with card slots, front view."
Decorative Images: When to Use Empty Alt Text
Not every image requires descriptive alt text. Purely decorative images — dividers, background patterns, icon flourishes that add no information — should have an empty alt attribute (alt=""), not a missing one. An empty alt attribute explicitly signals to screen readers and search engines that the image carries no informational value and should be skipped. A missing alt attribute is ambiguous — the browser has no instruction. Always include the attribute; its value depends on whether the image conveys information.
Alt Text for Different Image Types
Different image types need different alt text strategies. Infographics should have detailed alt text or a text alternative nearby. Charts and graphs should describe the key finding: "Bar chart showing 40% revenue growth in Q4 2025." Logos should state the company name. Product photos should describe the item, colour, and angle. Screenshots should describe what is shown on screen. Images used as links must describe the link's destination, not the image content — "Visit our pricing page" not "Screenshot of pricing table."
Finding Missing Alt Text at Scale
Large sites can have thousands of images, many uploaded over years by multiple contributors without alt text. A site crawler like SitemapFixer will identify every <img> tag with a missing or empty alt attribute across all pages. Export the report, filter by page traffic to prioritise high-value pages, and use the image filename as a starting point for writing descriptions — a file named blue-leather-wallet.jpg tells you more than IMG_4821.jpg.
Avoiding Common Alt Text Mistakes
The most common mistakes are keyword stuffing ("cheap shoes buy shoes discount shoes"), using filenames as alt text ("DSC00123.jpg"), writing identical alt text for multiple different images, and omitting alt text for images that convey information. Stuffed alt text triggers spam filters and actively harms rankings. Keep alt text human-readable first — if a description naturally includes a keyword, that is a bonus, not the primary goal.
Ongoing Alt Text Management
Prevent new images from being uploaded without alt text by enforcing it in your CMS. WordPress media library prompts for alt text on upload — make it a required field for your editorial team. For headless or custom builds, add form validation to image upload flows. Schedule quarterly crawls to catch any images that slipped through. Pairing CMS enforcement with regular audits ensures your alt text coverage stays close to 100% as the site grows.