Most people never think about alt text when uploading an image to a website.

But for someone using a screen reader, alt text is the only way they can understand what that image contains.

Alt text (alternative text) provides a text description of images, allowing screen readers to describe visual content to people who are blind or have low vision. It also helps search engines understand images and improves how your website content appears in search results.

But the benefits go beyond accessibility. Alt text can also help users on slow internet connections, people who turn images off to save data and anyone using voice technology to navigate websites.

In other words, good alt text helps everyone access your content more easily.

Here’s how to write alt text that is both accessible and effective.

1. Be Concise and Specific

Alt text should clearly describe the important content of an image without unnecessary detail.

Tips:

• Aim for one short sentence
• Keep descriptions under 125 characters where possible
• Focus on the key information the image communicates

Avoid phrases such as:

“image of”

“picture of”

Screen readers already announce that the content is an image, so repeating this adds unnecessary noise.

Instead, go straight to the meaningful description.

Example:

❌ Image of a teacher standing in a classroom holding a book

✅ Teacher holding a science textbook while explaining a lesson to students

2. Context Is Everything

The same image may require different alt text depending on how it is used.

Alt text should reflect the purpose of the image in that specific context, not just what it visually contains.

For example:

• If the image introduces a guest speaker, the alt text might simply be their name.
• If the same photo appears in an article about professional attire, the description may focus on their clothing.

For functional images, such as icons used as buttons or links, the alt text should describe the action.

Examples:

• “Download accessibility guide”
• “Submit form”

3. Handle Complex Visuals Separately

Charts, graphs, and infographics often contain too much information for a short alt text description.

In these cases:

• Use the alt text to summarise the main insight
• Provide a longer explanation nearby

Example alt text:

Bar chart showing a 20% increase in student engagement during term three.

Then provide a detailed explanation or data table below the image so all users can access the full information.

4. Know When to Leave Alt Text Blank

Not every image needs a description.

If an image is purely decorative, such as a background pattern, visual divider, or design element, it should use a null alt attribute:

alt=""

This tells screen readers to skip the image entirely, preventing unnecessary interruptions for users.

5. Optimise for SEO (Naturally)

Search engines rely on alt text to understand images, which can help your content appear in Google Image search results.

However, accessibility should always come first. Avoid keyword stuffing, which can harm both accessibility and SEO.

Instead:

• Write naturally
• Describe the image accurately
• Include relevant keywords only when they fit the description

Why Alt Text Matters

Writing good alt text helps meet WCAG 2.2 AA accessibility standards, specifically Success Criterion 1.1.1: Non-text Content.

More importantly, it ensures that people using assistive technology can access the same information as everyone else.

Plus, when websites are built with accessibility in mind, they tend to be clearer, more usable and more effective for all users.

Need Help Making Your Content Accessible?

Adding alt text is just one part of creating accessible digital content.

At Meet Aandi, we help organisations review and remediate websites, documents, and video content so they meet WCAG 2.2 accessibility standards.

If you're unsure whether your content is accessible, our team can audit your website and guide your team on best practices.

Because accessibility isn’t just about compliance, it’s about making information available to everyone.