Office of Inclusive Design

Alt-Text and Image Descriptions

Alt-text (alternative text) and image descriptions are written descriptions of visual content that make images accessible to people who are blind, have low vision, or use screen readers. They’re also helpful when images fail to load, for people with slow internet connections, and for improving search engine optimization (SEO).

Why they matter?
Individuals with vision impairments and those who use screen readers will face barriers to fully understanding visual content without alt-text or image descriptions. Additionally, people with cognitive disabilities, learning differences like dyslexia, or processing disorders benefit from having visual information available in text form.

This resource provides current guidelines for creating effective alt-text and image descriptions across platforms.

Alt-Text:
Short (under 125 characters ideally, max ~150)
Embedded in the image code/platform settings
Read by screen readers
Not visible to sighted users unless image fails to load
Best for: Quick, essential information

Image Descriptions:
Longer, more detailed (can be multiple sentences)
Written in the post caption or document body
Visible to everyone
Accessible to all users, not just screen reader users
Best for: Complex images, infographics, detailed charts, or when context matters

When to use which:
Social media: Use both when possible – alt-text for screen readers + image description in caption for everyone
Documents/presentations: Alt-text is essential; add extended descriptions in body text for complex visuals
Simple images: Alt-text alone may be sufficient
Complex images (charts, infographics, diagrams): Use both

Core Principles:
1. Be specific and descriptive

Write what you see, not what you think it means
Include relevant details that convey the purpose/context of the image

2. Be concise (for alt-text)

Most screen readers cut off around 125-150 characters
Get to the point quickly
Save longer descriptions for image description in captions

3. Describe what matters

Focus on information relevant to the content
Skip decorative or irrelevant details

4. Use clear, plain language

Avoid jargon unless necessary
Use active voice when possible

5. Include text that appears in the image

If there’s text on a graphic, flyer, or sign, include it word-for-word in the description
Example: “Purple graphic with white text reading ‘ASUW Spring Showcase, March 15, 6-9 PM'”

Microsoft Word (Updated 2026)
How to Add Alt-Text:
Right-click the image
Select “Edit Alt Text” from the menu
In the Alt Text pane on the right, write your description
Uncheck “Mark as decorative” (unless the image is purely decorative)
Close the pane
Accessibility Checker:
Go to Review > Check Accessibility
Word will flag images missing alt-text
Click each issue to add descriptions

When Exporting to PDF:
Go to File > Export > Create PDF/XPS
Click “Options”
Check “Document structure tags for accessibility”
This preserves your alt-text in the PDF

Google Docs (Updated 2026)
How to Add Alt-Text:
Click on the image
Right-click and select “Alt text”
Note: When you download as PDF, alt-text is preserved.

Adobe Acrobat Pro (Updated 2026)
How to Add Alt-Text to Existing PDFs:
Open your PDF in Acrobat Pro
Go to Tools > Accessibility > Reading Order
Click on an image
Right-click and select “Edit Alternate Text”
Type your description in the dialog box
Click “OK”
Close the Reading Order panel

Accessibility Checker:
Go to Tools > Accessibility > Full Check
Acrobat will identify images missing alt-text
Use the Results panel to add missing descriptions

Microsoft PowerPoint (Updated 2026)

How to Add Alt-Text:
Method 1: Right-click

  1. Right-click the image
  2. Select “Edit Alt Text” from the menu
  3. Type your description in the Alt Text pane
  4. Close the pane

Method 2: Accessibility Ribbon

  1. Select the image
  2. Go to Picture Format > Alt Text (in the ribbon)
  3. Type your description
  4. Close the pane

Mark as Decorative:

  • For purely decorative images (borders, design elements with no informational value), check “Mark as decorative”
  • This tells screen readers to skip the image

Accessibility Checker:
Go to Review > Check Accessibility

PowerPoint will flag missing alt-text
Fix issues directly from the checker pane

During Live Presentations:

  • Verbally describe visual content as you present
  • Don’t assume everyone can see the screen
  • Example: “This slide shows a bar chart comparing…”

Google Slides (Updated 2026)

  1. Click on the image
  2. Right-click and select “Alt text”
  3. In the sidebar:
    • Title: Brief label (optional)
    • Description: Your alt-text (required)
  4. Click outside the sidebar to close

During Live Presentations:

Describe visual content verbally
Share slides in advance when possible so people can review with assistive technology

If you need any additional support or have any questions alt-text, image descriptions or social media best practices please contact the Office of Inclusive Design (asuwoid@uw.edu/asuwoid1@uw.edu)