The Complete Guide to Writing Alt Text for Better SEO and Accessibility

1. Introduction

In a digital world where visuals dominate, writing effective alt text has become essential—not just for screen reader accessibility but also for improving search engine visibility. With the rising focus on web accessibility and inclusive design, every image on your website needs to pull double duty: enhancing UX and boosting SEO.

But how do you make sure your image descriptions are actually doing their job?

That’s where this guide comes in.

In this article, we’ll break down the alt text best practices that help you write compelling, useful, and SEO-friendly alt text—especially if you manage a content-heavy blog, eCommerce platform, or visual website.

2. What Is Alt Text?

Alt text, short for alternative text, is a written description added to an HTML image tag. Its main purposes are:

• Helping visually impaired users understand visual content via screen readers
• Allowing search engines to “see” and index your images
• Displaying fallback text if the image fails to load

Example of HTML alt text:

html

<img src=”reusable-water-bottle.jpg” alt=”Blue reusable water bottle on a white marble counter”>

That simple sentence enhances accessibility, improves SEO, and clarifies what the image is all about.

3. Why Alt Text Matters More Than Ever

Whether you’re managing a Shopify store, publishing blogs on WordPress, or running an enterprise website, writing alt text is crucial for:

Web Accessibility

Alt text allows screen readers to convey image content to blind or visually impaired users, fulfilling global standards like WCAG 2.1 and laws such as the ADA or EN 301 549 in the EU.

SEO Benefits

Google uses alt text to better understand and rank your page. Optimized alt text improves:

• Image rankings in Google Images
• Page context and relevance
• Overall on-page SEO
  

User Experience

Alt text helps users understand what’s on your page—even when images don’t load or they’re using assistive tech.

4. Alt Text Best Practices for 2025

Writing great alt text is a combination of accessibility, clarity, and strategy. Follow these best practices to get the most out of every image:

1. Be Descriptive, But Concise

Describe exactly what’s in the image—but keep it short and clear. Ideally under 125 characters, since some screen readers cut off longer descriptions.

Good: “Woman jogging on a forest trail during sunrise”
Bad: “Image of a woman doing physical exercise in nature with trees and sunlight and athletic shoes”

2. Avoid Starting with “Image of” or “Picture of”

Screen readers already announce it’s an image. Repeating that wastes valuable character space and time.

Better: “Golden retriever puppy sitting in a field of sunflowers”
Worse: “Image of a golden retriever puppy in a field of sunflowers”

3. Use Keywords, But Don’t Keyword-Stuff

If the image is relevant to your page’s focus, include a target keyword naturally.

Example:
If your page is about “eco-friendly kitchen products,” and the image is a bamboo cutting board, your alt text might be:
“Bamboo cutting board on a rustic wooden kitchen table”

Avoid keyword stuffing like: “eco-friendly cutting board eco cutting board eco bamboo board kitchen”

4. Explain the Function, Not Just the Form

If the image is a button, link, or has functionality (like icons), describe its purpose—not just what it looks like.

“Search icon to open search bar”
“Shopping cart icon to view items in cart”

5. Leave Decorative Images Blank

If an image is purely aesthetic (like a background or divider), it’s best to use empty alt text:

html

<img src=”divider.png” alt=””>

This tells screen readers to skip it, reducing noise and improving usability.

6. Context Matters

Describe the image based on what it represents in your content. The same image may need different alt text depending on context.

Example:

• On a product page: “Close-up of black vegan leather wallet with gold zipper”
• On a blog about sustainable materials: “Vegan leather wallet as an eco-friendly fashion accessory”
  

7. Consider AI Tools for Scaling Alt Text

If your site has hundreds or thousands of images, consider using AI alt text generators like AutoAlt.ai.

These tools help automate the process while still following alt text best practices, often combining image recognition with surrounding content analysis.

5. Common Mistakes to Avoid

• Writing vague or generic alt text like “image” or “photo”
• Duplicating the same alt text across multiple images
• Stuffing too many keywords
• Ignoring charts, infographics, and functional images
• Using alt text for every visual element—even when decorative

6. Examples of Well-Written Alt Text

7. Tools for Writing and Checking Alt Text

• AutoAlt.ai – AI-powered bulk alt text generator
• axe DevTools – Browser extension to check accessibility
• WAVE by WebAIM – Visual alt text analysis
• Screen Reader Simulators – Test how your site sounds to users with visual impairments

8. SEO Tips for Alt Text Optimization

• Use long-tail keywords sparingly and naturally
• Align image filenames with alt text when possible
• Avoid duplicating image titles and alt text—they serve different purposes
• Add structured data (if applicable) for rich image results

9. FAQs About Writing Alt Text

1. What makes good alt text?

Good alt text is descriptive, concise, and relevant. It describes the content and function of the image without keyword stuffing or unnecessary words.

2. How long should alt text be?

Alt text should be under 125 characters for maximum compatibility with screen readers. Stick to clear, helpful descriptions.

3. Do all images need alt text?

No. Only informative images should have alt text. Decorative images should have empty alt attributes (alt=””) to be skipped by screen readers.

4. Can I use the same alt text for multiple images?

No. Each image should have unique alt text based on its content and purpose to avoid confusing screen readers and hurting SEO.

5. What if I have hundreds of images?

Use AI-powered tools like Autoalt.ai to automatically generate accurate and context-aware alt text at scale.

10. Final Thoughts

Writing effective alt text isn’t just about ticking a box for accessibility—it’s a powerful way to improve SEO, enhance user experience, and reach a broader audience.

By following these alt text best practices, you’re not only building a more inclusive site but also creating stronger signals for search engines and users alike.

If you haven’t started optimizing your alt text yet, now is the time to take action. Whether you’re writing alt text manually or using smart AI tools like Autoalt.ai, consistent, meaningful alt text is a win-win for accessibility and SEO.