Write Effective Alt Text for Images

Questions

  • What is alt text and why does it matter?
  • How do I write good alt text for an image?
  • How do I add alt text to a picture in Word, PowerPoint, or Excel?
  • How long should alt text be?
  • What is a decorative image and how do I mark one?
  • How do I describe a chart or graph for a screen reader?

Environment

This article applies to Bowdoin faculty, staff, and students adding images to documents, slides, and other content. The steps below use Microsoft 365 apps, but the writing guidance applies anywhere you add alt text.

Resolution

Alt text (alternative text) is a short written description of an image that screen readers announce to people who cannot see it. Good alt text conveys both the content and the purpose of an image in its context.

Add alt text in Microsoft 365

  1. Right-click the image or object and choose View Alt Text (or select it and use Picture Format > Alt Text).
  2. Type one or two sentences describing the image and its purpose.
  3. If the image is purely decorative, select Mark as decorative instead of writing a description.

Write effective alt text

  • Be concise — usually a few well-chosen words to a sentence or two.
  • Convey the meaning, not just the object — include relevant context such as setting, expressions, or relationships.
  • Do not start with "image of" or "picture of" — screen readers already announce that it is a graphic.
  • Do not repeat nearby text, and do not use a file name or URL as alt text.

Special cases

  • Decorative images (borders, background flourishes) — mark as decorative so screen readers skip them.
  • Charts and graphs — describe the insight, not just the type. Instead of "a bar chart of sales," summarize the trend, and provide the underlying data nearby if it is complex.
  • Images that are links or buttons — describe where the link goes or what the button does.
Quick test: If you read your alt text aloud in place of the image, would the listener get the same information and purpose the image provides? If yes, it works.

Additional Help

If you need further assistance, you have several options:

  • Bowdoin Bot: Chat with Bowdoin Bot directly from any KB page for instant answers.
  • Phone: Call the Bowdoin College Service Desk at (207) 725-3030.
  • In person: Visit the Tech Hub in Smith Union during business hours.
  • Submit a ticket: Request assistance through the Service Catalog.

Additional Resources

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