Alt Text Best Practices 2025: Complete Guide + AI-Powered Generator

Alt text (alternative text) is a text description of images that screen readers announce to blind and visually impaired users. With 61 million Americans with disabilities and WCAG 2.2 mandating alt text for all informative images, proper image accessibility is both a legal requirement and business necessity.

This comprehensive 2025 guide covers everything you need to know about alt text, including AI-powered generation, when to use empty alt, complex image descriptions, and platform-specific implementation.

What you'll learn:

✅ When to use alt text vs. empty alt vs. ARIA labels
✅ How to write effective alt text (with examples)
✅ AI-powered alt text generation (vs. manual writing)
✅ Platform-specific guides (WordPress, Shopify, HTML)
✅ Testing alt text with screen readers
✅ Common mistakes and how to avoid them

What is Alt Text?
Why Alt Text Matters
When to Use Alt Text
How to Write Good Alt Text
Alt Text vs. Empty Alt vs. ARIA Labels
AI-Powered Alt Text Generation
Platform-Specific Implementation
Complex Images and Long Descriptions
Testing Alt Text
Common Alt Text Mistakes
Free AI Alt Text Generator

What is Alt Text?

Alt text (alternative text, alt attribute, or alt tag) is HTML code that describes the content and function of an image. It appears in the alt attribute of the <img> tag:

<img src="golden-retriever-puppy.jpg" alt="Golden retriever puppy playing with tennis ball in grass">

Who uses alt text?

Screen reader users (blind/visually impaired) - Alt text is read aloud
Search engines - Alt text helps Google understand images
Users with images disabled - Alt text displays when images don't load
Users with slow connections - Alt text appears while images load

WCAG Requirements:

WCAG 1.1.1 Non-text Content (Level A): All informative images must have text alternatives
Failure to provide alt text = accessibility violation = potential lawsuit

Why Alt Text Matters

1. Legal Compliance

United States:

4,605 ADA website lawsuits filed in 2024
Missing alt text = #1 most common accessibility violation (85% of sites)
Average settlement: $25,000-$75,000
Domino's Pizza v. Robles (2019): Website accessibility required

European Union:

European Accessibility Act (EAA) now in force since June 28, 2025
Missing alt text = non-compliance
Penalties up to €100,000 or 4% of annual revenue

2. SEO Benefits

Google Image Search:

Alt text is a ranking factor for image search
Improves visibility in Google Images
Helps Google understand page context

Example SEO impact:

E-commerce site with 1,000 products
Added descriptive alt text to all product images
32% increase in organic traffic from image search within 3 months

3. User Experience

Screen reader users:

26 million Americans have vision impairments
Alt text enables shopping, research, entertainment
Good alt text = better customer experience = higher conversion

All users:

Alt text appears when images fail to load
Helps users on slow connections
Provides context when images are disabled

When to Use Alt Text

Decision Tree

Ask: "Does this image convey information or have a function?"

YES → Use descriptive alt text

Product images (e-commerce)
Informational graphics, charts, diagrams
Logos that also serve as links
Photos illustrating article content
Icons with meaning (social media icons)
Buttons created as images
Maps, screenshots, infographics

NO → Use empty alt (alt="")

Decorative images (flourishes, dividers, backgrounds)
Images used purely for visual design
Images where adjacent text already describes them
Icons next to text labels (redundant)

How to Write Good Alt Text

The Golden Rules

1. Be Descriptive but Concise

Describe what you see
Keep under 125 characters (screen reader limit)
Focus on important details

2. Don't Say "Image of" or "Picture of"

Screen readers announce "Image" already
Redundant and wastes characters

3. Describe the Content, Not the Medium

❌ "Photo of a dog"
✅ "Golden retriever puppy playing with tennis ball"

4. Include Context When Relevant

Consider why the image is included
Describe relevant details for understanding

5. Don't Include Filename or Technical Details

❌ "IMG_1234.jpg"
❌ "dog-photo-800x600.png"

Examples: Product Images

E-commerce product page:

<!-- BAD: Too vague -->
<img src="shirt.jpg" alt="Shirt">

<!-- BAD: Redundant -->
<img src="shirt.jpg" alt="Image of a shirt">

<!-- BAD: Technical details -->
<img src="shirt.jpg" alt="shirt-blue-medium.jpg">

<!-- GOOD: Descriptive, includes relevant details -->
<img src="shirt.jpg" alt="Men's blue cotton t-shirt, crew neck">

<!-- EVEN BETTER: Includes variation if multiple options -->
<img src="shirt.jpg" alt="Men's blue cotton t-shirt, crew neck, available in sizes S-XXL">

Why the last example is best:

Identifies the product (t-shirt)
Describes appearance (blue, cotton, crew neck)
Specifies audience (men's)
Includes availability info (sizes)

Examples: Informational Images

Blog post photo:

<!-- BAD -->
<img src="meeting.jpg" alt="Meeting">

<!-- GOOD -->
<img src="meeting.jpg" alt="Three colleagues discussing project at whiteboard">

<!-- EVEN BETTER: Contextual -->
<img src="meeting.jpg" alt="Software developers collaborating on system architecture diagram at whiteboard">

Icon with text label:

<!-- When icon appears NEXT TO text (redundant, use empty alt) -->
<a href="/cart">
  <img src="cart-icon.svg" alt="">
  Shopping Cart (3 items)
</a>

<!-- When icon appears WITHOUT text (use descriptive alt) -->
<a href="/cart">
  <img src="cart-icon.svg" alt="Shopping cart (3 items)">
</a>

Examples: Functional Images

Logo that links to homepage:

<!-- GOOD: Describes function -->
<a href="/">
  <img src="logo.png" alt="AllAccessible home">
</a>

<!-- ALSO GOOD: Company name + function -->
<a href="/">
  <img src="logo.png" alt="AllAccessible - Return to homepage">
</a>

Social media share buttons:

<!-- GOOD: Describes action -->
<button>
  <img src="twitter-icon.svg" alt="Share on Twitter">
</button>

<!-- ALSO GOOD: More specific -->
<button>
  <img src="twitter-icon.svg" alt="Share this article on Twitter">
</button>

Search button:

<!-- GOOD -->
<button type="submit">
  <img src="magnifying-glass.svg" alt="Search">
</button>

Alt Text vs. Empty Alt vs. ARIA Labels

When to Use Each

Scenario	Solution	Example
Informative image	`alt="description"`	Product photos, charts, meaningful icons
Decorative image	`alt=""`	Borders, dividers, background patterns
Redundant image	`alt=""`	Icon next to text saying the same thing
Complex image	`alt="summary"` + long description	Charts, diagrams, infographics
CSS background image	Use ARIA or HTML text	Hero backgrounds with text overlay

Empty Alt (`alt=""`)

When to use:

Decorative images that don't convey information
Images where adjacent text already describes them
Icons that are purely visual enhancements

Examples:

<!-- Decorative border image -->
<img src="decorative-border.png" alt="">

<!-- Icon next to text label (redundant) -->
<button>
  <img src="download-icon.svg" alt="">
  Download PDF
</button>

<!-- Decorative photo on marketing page -->
<section class="hero">
  <img src="abstract-background.jpg" alt="">
  <h1>Welcome to Our Service</h1>
</section>

Why empty alt, not removing alt entirely?

Without alt attribute: Screen reader announces filename ("decorative-dash-border-dash-line.png")
With alt="": Screen reader skips image entirely
Always include alt attribute, even if empty

ARIA Labels for Background Images

Problem: CSS background images don't have alt text

Solution: Use ARIA labels or visible text

<!-- CSS background image with ARIA label -->
<div class="hero-banner" 
     style="background-image: url('mountain-landscape.jpg')"
     role="img"
     aria-label="Mountain landscape at sunset with snow-capped peaks">
  <h1>Explore the Outdoors</h1>
</div>

<!-- Better: Use visible caption -->
<figure>
  <div class="hero-banner" style="background-image: url('mountain-landscape.jpg')"></div>
  <figcaption class="visually-hidden">Mountain landscape at sunset with snow-capped peaks</figcaption>
</figure>

AI-Powered Alt Text Generation

Manual vs. AI Alt Text

Manual alt text writing:

✅ Contextually accurate
✅ Includes brand-specific details
❌ Time-consuming (2-5 minutes per image)
❌ Inconsistent quality
❌ Not scalable for large sites

AI-powered alt text:

✅ Fast (seconds per image)
✅ Consistent format
✅ Scalable (thousands of images)
✅ Good baseline descriptions
❌ May miss context
❌ Requires human review for accuracy

How AI Alt Text Works

Modern agentic AI (like AllAccessible AI):

Analyzes image pixels
Identifies objects, people, text, scenes
Generates natural-language descriptions tuned for accessibility
Applies best practices (concise, descriptive, context-aware)

Example AI-generated alt text:

Input image: Photo of a woman using a laptop at a coffee shop

AI output: "Woman working on laptop at cafe table with coffee cup"

Human refinement: "Business professional using MacBook at outdoor cafe, coffee and notebook on table"

(Human adds context: business professional, MacBook brand, outdoor setting)

When to Use AI Alt Text

✅ Good use cases:

Large product catalogs (e-commerce)
Stock photos on blog posts
User-generated content (social media, reviews)
Legacy content with missing alt text
Initial baseline for human review

❌ Not recommended:

Critical images (homepage hero, key products)
Images requiring brand-specific language
Images with embedded text (use OCR + manual)
Charts and diagrams (complex images need manual)

AI Alt Text Best Practices

1. Always Review AI Output

AI provides baseline, humans add context
Check for accuracy and relevance
Add brand-specific terminology

2. Combine AI + Human Workflow

1. AI generates alt text for all images
2. Humans review high-priority images (homepage, top products)
3. Accept AI suggestions for low-priority images (blog archives)

3. Train AI on Your Content

Provide examples of good alt text for your products
Use brand style guide terminology
Create templates for common image types

Platform-Specific Implementation

WordPress

Method 1: Media Library (Recommended)

Go to Media → Library
Click on image
Enter alt text in Alternative Text field
Click Update

Method 2: While Adding to Post

Insert image into post/page
Click image → Click pencil icon (Edit)
Enter alt text in Alternative Text field
Click Update

Code (if editing theme files):

<?php
// Get featured image with alt text
if (has_post_thumbnail()) {
  echo get_the_post_thumbnail(
    get_the_ID(),
    'large',
    array('alt' => get_post_meta(get_post_thumbnail_id(), '_wp_attachment_image_alt', true))
  );
}
?>

WordPress Plugins for AI Alt Text:

AllAccessible for WordPress - AI-powered alt text generation
ImageSEO - Automatic alt text with AI
WP Accessibility - Accessibility checks including alt text

Shopify

Method 1: Product Admin

Go to Products → Select product
Click on image
Click Add alt text
Enter description
Click Save

Method 2: Theme Code (Liquid)

{%- comment -%}
  Product image with alt text
{%- endcomment -%}

{% if product.featured_image %}
  <img
    src="{{ product.featured_image | image_url: width: 800 }}"
    alt="{{ product.featured_image.alt | default: product.title | escape }}"
    width="800"
    height="800"
  />
{% endif %}

{%- comment -%}
  Fallback: If merchant didn't add alt text, use product title
{%- endcomment -%}

Shopify Apps for Alt Text:

AllAccessible for Shopify - Automated alt text for products
SEO Image Optimizer - Bulk alt text editing

HTML (Hand-Coded Sites)

Basic image:

<img src="/images/product-laptop.jpg" 
     alt="Silver 15-inch laptop, open with blank screen"
     width="800"
     height="600">

Responsive images with srcset:

<img 
  srcset="
    /images/product-small.jpg 400w,
    /images/product-medium.jpg 800w,
    /images/product-large.jpg 1200w
  "
  sizes="(max-width: 600px) 400px,
         (max-width: 1000px) 800px,
         1200px"
  src="/images/product-medium.jpg"
  alt="Wireless bluetooth headphones, black with silver accents"
  width="800"
  height="600">

Picture element with multiple sources:

<picture>
  <source media="(min-width: 800px)" srcset="/images/hero-desktop.jpg">
  <source media="(min-width: 400px)" srcset="/images/hero-tablet.jpg">
  <img src="/images/hero-mobile.jpg" 
       alt="Team collaboration in modern office, people working together at whiteboard"
       width="400"
       height="300">
</picture>

Complex Images and Long Descriptions

Complex images (charts, diagrams, infographics) need more than 125 characters.

Solution: Short alt + long description

Method 1: Adjacent Text

<figure>
  <img src="sales-chart-2024.png" 
       alt="Bar chart showing quarterly sales growth in 2024">
  <figcaption>
    <details>
      <summary>Chart description</summary>
      <p>
        Bar chart showing quarterly sales for 2024. Q1: $2.5M, Q2: $3.1M (24% increase),
        Q3: $3.8M (23% increase), Q4: $4.2M (11% increase). Overall annual growth: 68%.
      </p>
    </details>
  </figcaption>
</figure>

Method 2: aria-describedby

<img src="complex-diagram.png"
     alt="System architecture diagram"
     aria-describedby="diagram-description">

<div id="diagram-description">
  <p>
    The diagram shows a three-tier architecture with a React frontend,
    Node.js API server, and PostgreSQL database. The frontend communicates
    with the API via HTTPS on port 443. The API connects to the database
    on port 5432. A Redis cache sits between the API and database for
    performance optimization.
  </p>
</div>

Method 3: Link to Full Description

<figure>
  <img src="infographic.png" 
       alt="Accessibility statistics infographic - see full description below">
  <figcaption>
    <a href="#infographic-description">Full description of infographic</a>
  </figcaption>
</figure>

<div id="infographic-description">
  <h2>Accessibility Statistics Infographic Description</h2>
  <p>The infographic contains the following statistics:</p>
  <ul>
    <li>61 million Americans have a disability (26% of adults)</li>
    <li>$13 trillion global disability market</li>
    <li>4,605 ADA lawsuits filed in 2024</li>
    <li>27% higher conversion rates on accessible sites</li>
  </ul>
</div>

Testing Alt Text

Automated Testing

axe DevTools (Browser Extension):

Install from Chrome/Firefox extension store
Open page with images
Click "Scan ALL of my page"
Review "Images must have alternate text" violations

WAVE (WebAIM):

Visit https://wave.webaim.org/
Enter your URL
Review red icons for missing alt text
Review yellow alerts for suspicious alt text (filenames, "image of", etc.)

Manual Testing with Screen Readers

NVDA (Windows - Free):

Download from https://www.nvaccess.org/
Install and launch NVDA
Navigate to page with images
Press G to jump to next graphic
Listen to alt text announcement

What you should hear:

✅ "Graphic, Golden retriever puppy playing with tennis ball in grass"
❌ "Graphic, IMG underscore 1234 dot JPG" (filename = missing alt text)
❌ "Graphic" (no description = missing alt text)

VoiceOver (Mac - Free):

Press Cmd+F5 to enable VoiceOver
Navigate to page
Press VO+Right Arrow to move through elements
Listen to image descriptions

Browser Developer Tools

Chrome DevTools:

Right-click image → Inspect
Look for alt attribute in HTML
Accessibility pane shows computed name

Firefox Accessibility Inspector:

Right-click image → Inspect Element
Click Accessibility tab
View "Name" property (should show alt text)

Common Alt Text Mistakes

1. Using Filenames

<!-- BAD: Filename as alt text -->
<img src="IMG_1234.jpg" alt="IMG_1234.jpg">

<!-- GOOD: Descriptive alt text -->
<img src="IMG_1234.jpg" alt="Close-up of fresh strawberries in wooden basket">

2. Starting with "Image of" or "Picture of"

<!-- BAD: Redundant -->
<img src="dog.jpg" alt="Image of a dog">

<!-- GOOD: Concise -->
<img src="dog.jpg" alt="Golden retriever puppy sitting in grass">

3. Alt Text Too Long

<!-- BAD: Over 125 characters -->
<img src="team.jpg" alt="Our amazing team of software engineers, designers, product managers, and customer success specialists working together in our beautiful modern office space with lots of natural light and ergonomic furniture to create the best possible products for our customers">

<!-- GOOD: Concise, under 125 characters -->
<img src="team.jpg" alt="Software development team collaborating in modern office">

4. Missing Alt for Decorative Images

<!-- BAD: Descriptive alt for decorative image -->
<img src="decorative-line.png" alt="Blue horizontal line">

<!-- GOOD: Empty alt -->
<img src="decorative-line.png" alt="">

5. Duplicate Alt Text

<!-- BAD: Alt text same as adjacent heading -->
<h1>Contact Us</h1>
<img src="contact-icon.svg" alt="Contact Us">

<!-- GOOD: Empty alt (redundant with heading) -->
<h1>Contact Us</h1>
<img src="contact-icon.svg" alt="">

Free AI Alt Text Generator

How It Works

AllAccessible's AI Alt Text Generator uses AllAccessible AI vision models to analyze images and generate WCAG-compliant alt text in seconds.

Features:

✅ Upload any image (JPG, PNG, WebP)
✅ AI analyzes content and context
✅ Generates concise, descriptive alt text
✅ Provides multiple variations to choose from
✅ Checks alt text length (<125 characters)
✅ Free to use (no signup required)

Try it now: AllAccessible AI Alt Text Generator →

Conclusion

Alt text is essential for accessibility, SEO, and user experience. With AI-powered generation tools, adding alt text is faster than ever—but human review ensures accuracy and context.

Key Takeaways:

✅ Use descriptive alt text for informative images
✅ Use empty alt (alt="") for decorative images
✅ Keep alt text under 125 characters
✅ Don't say "image of" or use filenames
✅ Use AI to accelerate, but always review
✅ Test with screen readers (NVDA, VoiceOver)
✅ Platform-specific implementation (WordPress, Shopify, HTML)

Next Steps:

Audit your site with axe DevTools or WAVE
Identify images missing alt text
Use AI generator for baseline descriptions
Review and refine AI-generated alt text
Test with screen reader to verify

Need help? AllAccessible provides automated alt text generation with AI and real-time accessibility monitoring. Start free trial →

Published: November 13, 2025 Last Updated: November 13, 2025 Reading Time: 20 minutes

About AllAccessible: We provide AI-powered accessibility solutions including automated alt text generation, real-time WCAG monitoring, and comprehensive remediation tools. Learn more at allaccessible.org.

Alt Text Best Practices 2025: Complete Guide + AI-Powered Generator

Alt Text Best Practices 2025: Complete Guide + AI-Powered Generator

Table of Contents

What is Alt Text?

Why Alt Text Matters

1. Legal Compliance

2. SEO Benefits

3. User Experience

When to Use Alt Text

Decision Tree

How to Write Good Alt Text

The Golden Rules

Examples: Product Images

Examples: Informational Images

Examples: Functional Images

Alt Text vs. Empty Alt vs. ARIA Labels

When to Use Each

Empty Alt (alt="")

ARIA Labels for Background Images

AI-Powered Alt Text Generation

Manual vs. AI Alt Text

How AI Alt Text Works

When to Use AI Alt Text

AI Alt Text Best Practices

Platform-Specific Implementation

WordPress

Shopify

HTML (Hand-Coded Sites)

Complex Images and Long Descriptions

Method 1: Adjacent Text

Method 2: aria-describedby

Method 3: Link to Full Description

Testing Alt Text

Automated Testing

Manual Testing with Screen Readers

Browser Developer Tools

Common Alt Text Mistakes

1. Using Filenames

2. Starting with "Image of" or "Picture of"

3. Alt Text Too Long

4. Missing Alt for Decorative Images

5. Duplicate Alt Text

Free AI Alt Text Generator

How It Works

Conclusion

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Empty Alt (`alt=""`)