Writing Effective Alt Text

Why This Matters

Alt text ensures that people who use screen readers can access the meaning and purpose of visual content. Without it, key information is lost. Effective alt text improves clarity, inclusion, and engagement.

Core Concept: Purpose Over Description

Alt text should communicate the purpose of an image, not just list visual details. Ask: What is this image doing in this post?

Guidelines for Writing Alt Text

• Start with the type of image only if necessary (e.g., chart, infographic).

• Describe the main action or message first.

• Include important visual details that support understanding.

• Keep it concise but complete.

• Avoid redundancy with surrounding text.

• Do not use phrases like 'image of' unless needed for clarity.

Decorative vs. Informative Images

Decorative images do not add meaning and can have empty alt text.

Informative images must have descriptive alt text that conveys their purpose.

Examples

Poor: "A person holding a phone"

Better: "Person using a smartphone with a screen reader to navigate an app"

Poor: "Graph with a line going up"

Better: "Line graph showing a steady increase in accessibility compliance from 2022 to 2025"

Advanced Situations

Charts: Summarize key trends, not every data point.

Memes: Convey both the visual and the joke or tone.

Branding: Focus on what the image communicates, not just the logo.

Quick Checklist

• Does the alt text reflect the image’s purpose?

• Is the main message clear?

• Is it concise?

• Does it avoid redundancy?

• Would it make sense without seeing the image?