ADA Alternative Text

Best Practices for Writing Alt Text

Match the Image’s Purpose 

• Alt text should convey the function or meaning of the image in its context—not just describe what it looks like. 
• Ask: “Why is this image here? What does the user need to know?” 
• If the image is decorative and provides no meaningful info, use: alt=""  
  (This hides it from screen readers.) 

Be Clear, Concise & Accurate 

• Alt text should be brief but meaningful, typically under 125 characters (a common guideline because many screen readers pause after that length). 
• Include only the information necessary to understand the content. 
• Avoid overly technical or vague wording. 

When screen reader users encounter multiple images with the same or nearly identical alt text: 

• They can’t tell images apart. 
• They may think they’re hearing the same image repeated. 
• Navigation becomes confusing and frustrating. 

Use repeated alt text when: 

• The images are identical (e.g., the same college logo used multiple times). 
• The images have the same function (e.g., two search icons both labeled alt="Search"). 

Do NOT Start with “Image of…” 

• Screen readers already announce that it’s an image. Jump straight into the relevant information. 

❌ “Image of a dog playing fetch.” 
✅ “Golden retriever catching a tennis ball.” 

Describe Only What Users Need to Know 

• Provide only details relevant to the content or purpose. 
• If an image is used for instruction, include the details needed to follow along. 
• If it’s for context, describe what contributes to that context. 

Include Text That Appears in the Image 

• If text in the image is important, it must be in the alt text. 
• Example: a graphic with the words “Fall Registration Deadline: August 1” 
• Include the text exactly—this is essential for accessibility and compliance. 

Avoid Redundant Information 

• If the caption or surrounding text already covers what the image conveys, simplify or leave alt text empty (if purely decorative). 

Consider the Audience 

• Use language that matches the reading level and knowledge of your intended users. Avoid jargon unless the context specifically requires it. 

Maintain Objectivity 

• Describe factual elements, not assumptions or interpretations. 

❌ “A happy student holding a laptop.” 
✅ “Student smiling while holding an open laptop.” 

Test with a Screen Reader 

• Even if you don’t rely on one, testing is one of the best ways to ensure accessibility. 
• NVDA (free, Windows) 
• VoiceOver (built into macOS and iOS) 

Common Mistakes 

• Many people who write alt text for images make these common errors: 
• The text is too short and doesn’t describe the relevant content of the image. 
• The text is too long and describes unnecessary information. 
• The text visually describes the image but does not say why the image was included in the content. 
• The text repeats information from the main text. 
• The alt text is just the image’s file name or path instead of a description.   

For more information, review the alt text techniques described at WebAim or see Authoring Meaningful Alternative Text. 

Use thoughtful text descriptions

• Each image should have a description (alt text) that describes what is in the image.
• It is easy to use simple words like image or picture for your alt text, but that is bad practice and breaks accessibility – and it is mean to the user.
• If you are using an image as an action (using a picture that looks like a button), then the alt text should describe the action
• If you use AI, read the description thoroughly to ensure if follows the guidelines listed in this resource.