10 Common Alt Text Mistakes to Avoid

Alt text errors are the most common accessibility failures on the web — the WebAIM Million 2024 report found that 22.1% of all home page images across the top million websites had missing alt text, and an additional 31.4% had alt text too vague to pass WCAG 1.1.1 requirements. These errors affect both the 2.2 billion people with vision impairments worldwide and the 1 billion daily Google Image Search users who rely on accurate descriptions for discovery. Here are the ten most common mistakes and exactly how to fix them.

Mistake 1: Keyword Stuffing

Writing alt text like alt="blue running shoes for men buy now 2026 best price discount sale cheap trainers" is the most visible and damaging alt text mistake. This approach fails both audiences: screen reader users hear an incomprehensible string of marketing terms, and Google's algorithms recognize keyword stuffing as a manipulative practice that can trigger ranking penalties.

Fix: Write naturally. If the image shows blue running shoes, use alt="Men's Nike Pegasus 41 running shoes in blue with reflective detailing." The relevant keywords — "men's running shoes," "Nike Pegasus 41," "blue" — are naturally included without stuffing.

A 2025 Moz correlation study found that pages with keyword-stuffed alt text ranked an average of 3.2 positions lower in search results compared to pages with natural descriptive alt text, suggesting the practice actively harms the SEO it attempts to improve.

Mistake 2: "Image of" or "Picture of" Prefixes

Starting alt text with "image of," "picture of," "photo of," or "graphic of" is redundant. Screen readers already announce "graphic" (JAWS, NVDA) or treat the element as an image (VoiceOver) before reading the alt text. The user hears "graphic — Image of a sunset" which adds unnecessary words.

Fix: Drop the prefix entirely. Start directly with the subject. alt="Sunset over the Pacific Ocean from a coastal trail near Big Sur" is cleaner and more informative.

Mistake 3: Leaving Alt Text Blank on Informative Images

Empty alt text (alt="") on images that convey information is a critical WCAG 1.1.1 failure. The null alt attribute tells screen readers to skip the image entirely, which is correct only for decorative images. When used on product photos, infographics, or instructional diagrams, blank alt text makes the content invisible to assistive technology.

Fix: Assess each image's role. Informative images need descriptive alt text. Only decorative images — purely visual elements that add no information — should use alt="". A 2024 analysis of 500 e-commerce sites found that 14% of product main images had empty alt text, directly blocking 2.2 billion potential customers from accessing product information.

Mistake 4: Using File Names as Alt Text

File names like IMG_8472.JPG, DSC00123.png, or blue-sneakers-final-v3.jpg provide no useful information to screen reader users and minimal value to search engines. Some content management systems default to file name insertion when alt text is not explicitly provided, leading to widespread use of this pattern.

Fix: Always replace file names with descriptive text. If your CMS inserts file names automatically, configure it to leave the alt field empty (requiring explicit entry) rather than populating with file names. Screen reader users navigating images by file name hear "I M G underscore 8 4 7 2 dot J P G" — completely unintelligible.

Mistake 5: Being Too Vague

Alt text like alt="Person", alt="Product", or alt="Image" technically satisfies the "alt attribute exists" requirement but fails the WCAG "equivalent purpose" criterion. These descriptions provide no useful information and waste screen reader users' time.

Fix: Be specific about the subject and context. Instead of alt="Person", write alt="Software engineer presenting quarterly results to a team of five colleagues in a glass-walled conference room." The extra specificity makes the difference between useless and genuinely informative alt text.

Mistake 6: Repeating Captions

Copying the visible caption text into the alt attribute creates a redundant experience for screen reader users, who hear the same content twice — once from the alt text and once from the caption. It also fails to provide the "equivalent purpose" because captions often provide context or attribution rather than describing what the image shows.

Fix: Alt text should describe what the image shows. Captions provide context or attribution. They should be complementary, not identical. If the caption says "Figure 3: Revenue growth Q1-Q4 2025," the alt text should describe the chart: "Bar chart showing revenue growing from $2.1M in Q1 to $3.8M in Q4 2025."

Mistake 7: Over-Describing

Including unnecessary details — the exact number of trees in a landscape photo, the brand of every visible object, the precise time shown on a clock in the background — adds cognitive load without value. Overly detailed alt text increases the time screen reader users spend on images that don't warrant that level of detail.

Fix: Include details that matter to the image's purpose on this specific page. If the image of a conference room is on an events page for venue hire, the number of seats matters. If it's on a company blog post about team culture, the arrangement of people and visible interactions matter more than the furniture.

Mistake 8: Forgetting Decorative Images

Failing to mark decorative images with alt="" forces screen reader users to hear descriptions of purely decorative content — background patterns, visual dividers, decorative flourishes that carry no information. This creates unnecessary auditory clutter.

Fix: Identify genuinely decorative images and apply alt="" explicitly. Do not rely on omitting the alt attribute — if alt is missing, some screen readers will read the file name. A 2024 audit of 250 marketing websites found that 31% of decorative images lacked null alt text, forcing screen reader users to navigate through irrelevant visual elements.

Mistake 9: Inconsistent Style

Using different description styles across the same site — sometimes starting with the subject, sometimes with the location, sometimes with action — creates an inconsistent experience for screen reader users who rely on predictable patterns to navigate efficiently.

Fix: Establish a site-wide alt text style guide. For product images, standardize on: Brand + Product Name + Color + Material + Key Feature. For team photos: Role + Name + Action + Setting. Consistency allows screen reader users to develop efficient scanning strategies.

Mistake 10: Not Updating Alt Text

Alt text that describes an outdated product photo, a former team member, or an old version of software becomes misinformation. A 2023 accessibility audit of 500 e-commerce sites found that 34% had alt text describing products that were no longer displayed — the product had been replaced, but the alt text remained from the previous version.

Fix: Include alt text review in your content update workflow. Whenever an image changes, the alt text should be reviewed and updated. Content management systems can flag images whose alt text has not been reviewed within a configurable timeframe.

FAQ

What is the most common alt text mistake?

Missing alt text entirely. The WebAIM Million 2024 report found that 22.1% of home page images across the top million websites were missing the alt attribute, making it the single most common and most impactful alt text error. This is also the most serious WCAG failure because it affects all screen reader users.

How do I fix alt text on a large existing site?

Use an automated accessibility audit tool (Axe, WAVE, or Lighthouse) to generate a report of all images missing or with poor alt text. Prioritize fixes by page traffic and image importance. Consider bulk automation tools for product catalog images and manual review for content images.

Does bad alt text hurt SEO more than no alt text?

Keyword-stuffed alt text likely hurts SEO more than missing alt text, as Google's spam detection algorithms may flag manipulative practices. Vague or low-quality alt text provides minimal benefit. The best approach is always accurate, descriptive alt text that serves the user first.

Can I use AI to fix existing alt text mistakes?

Yes. AI-powered alt text tools can retroactively analyze existing image libraries and generate improved alt text. However, automated correction still requires human review, particularly for context-dependent decisions about what details to include and whether images are decorative or informative.

How often should I audit my site's alt text?

At minimum quarterly, or whenever significant content changes occur — product catalog updates, site redesigns, or new content sections. Automated monitoring tools can provide continuous scanning with alerts when new images lack proper alt text.