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Introduction
Alternative text (alt text) describes the content and purpose of images, charts, and other visual elements in words, so people who use screen readers or who cannot view the visuals can still understand the information. Good alt text is concise, specific, and focused on what matters in context, and it should convey key information from visuals rather than decorative details. This guide explains how to add and review accessible alt text in Microsoft Word, Google Docs, PowerPoint, and Google Slides.
Why It Matters
Screen readers can’t interpret images without support. Accessible images ensure people who are blind or have low vision (and anyone using text-only or low-bandwidth views) get the same information.
Before You Review Your Images, Are You Using Them Correctly?
- Avoid images of text: If someone must read the words to understand the content, those words should be available as real text in the document (or provided as a nearby transcription). Alt text can summarize, but it shouldn’t be the only place long text appears.
- Meaningful vs. decorative: If an image is only decorative, consider removing it or marking it as decorative so it doesn’t add noise for screen reader users. Decorative images don't add information to the context of the page.
- Complex visuals need more: If the image is complex (chart/diagram), provide a short summary in nearby text and include the key takeaways, not only alt text.
Writing Good Alt Text
Good alt text succinctly describes the purpose of an image. It should convey the enhanced level of understanding the original image provides.
- Accurate: correctly describes the content or purpose of the image.
- Short: a few words to a few sentences, ideally 150 characters or less.
- Contextual: communicate the purpose of the image in its context. Answer "why is this here?" not just "what does this show?"
- Not repetitive: don't begin alt text with "image of" or repeat any description of the image given in the caption or surrounding text. Screen readers already identify that an image is present.
How to Add Alt Text to Images
Microsoft Word / PowerPoint
- Select the image, right click and select “Alt Text”
- A side pane appears on the right and “Alt Text” will show expanded
- Enter a description. If the image is decorative, leave the description blank.
- In documents, avoid floating images that can disrupt reading order
- When possible, set images to In Line with Text
- Don’t rely on images of text. Provide the text in the document.
Google Docs / Slides
- Right click the image and select "Alt Text"
- In the "Image options" pane, enter the description of the image
- If the image is decorative, leave the description blank
- In documents, avoid floating images that can disrupt reading order
- When possible, set images to In Line with Text
- Don’t rely on images of text. Provide the text in the document.
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