Best Practices for Writing Accessible Alt Text for Images

Introduction

Alt text (alternative text) plays a vital role in making your website accessible. It provides textual descriptions of images, ensuring that users with visual impairments can understand the content through screen readers. Writing effective alt text is not only essential for inclusivity but also helps meet WCAG and ADA compliance standards. This guide will cover best practices for crafting accessible alt text for images.

1. Be Concise but Descriptive

Alt text should provide enough detail to describe the image’s content and purpose without being overly verbose. Aim for a clear and concise description that conveys the image’s essential information.

Example: For an image of a person walking a dog in a park, use alt text like: “Person walking a golden retriever in a park with trees.”

2. Avoid Redundant Phrases

Screen readers already indicate that an element is an image, so avoid phrases like “Image of” or “Picture of.” Jump straight into the description.

Tip: Write alt text as if you’re describing the image to someone over the phone.

3. Focus on Context and Purpose

Consider the image’s role on the page when writing alt text. If the image provides essential information, describe it in detail. If it’s decorative, consider marking it as such (see next section).

Example: For a product image on an e-commerce site, use alt text like: “Blue running shoes with white soles, side view.”

4. Mark Decorative Images as Null

Decorative images that do not convey meaningful content should be marked with an empty alt attribute (alt=""). This tells screen readers to skip over the image, reducing unnecessary interruptions.

Tip: Use null alt text for images like background patterns or purely aesthetic graphics.

5. Avoid Overloading with Keywords

While alt text can improve SEO, avoid keyword stuffing. Overloading alt text with irrelevant keywords can confuse users and reduce accessibility.

Bad Example: “SEO tips, marketing strategies, website design, web accessibility tips, golden retriever in park.”

Good Example: “Person walking a golden retriever in a park with trees.”

6. Use Accurate and Neutral Language

Ensure that your descriptions are factual and avoid inserting personal opinions or assumptions. Focus on what the image visually represents.

Example: Instead of “A stunning sunset,” use “A sunset over a mountain range with orange and pink hues.”

7. Include Text in Images

If an image contains important text (e.g., a logo or infographic), include the text content in the alt text. This ensures users who rely on screen readers can access the same information.

Example: For a company logo: “Company logo: TechCo with a blue and green gradient.”

8. Prioritize Accessibility for Complex Images

For charts, graphs, or infographics, provide a brief description in the alt text and link to a longer, detailed explanation if necessary.

Example: “Bar graph showing sales growth from 2020 to 2024. Full description below.”

9. Test with Screen Readers

After adding alt text, test your website with a screen reader like NVDA or VoiceOver to ensure the descriptions are clear and helpful.

10. Keep Alt Text Updated

Regularly review and update alt text as your website content evolves. Ensure new images are properly described and align with accessibility standards.

Conclusion

Writing accessible alt text is a simple yet impactful way to make your website more inclusive. By following these best practices, you can improve the user experience for individuals with disabilities while ensuring compliance with accessibility standards like WCAG and ADA. Start crafting thoughtful and descriptive alt text today to create a more inclusive digital space.