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If a picture is worth a thousand words, what's it worth to people who cannot see? Without words, it's easy for people with a visual disability to miss critical information or get frustrated with the experience.
Alternative text (alt text) is descriptive text which conveys the meaning and context of a visual item in a digital setting, such as on an app or web page. When screen readers like Microsoft Narrator, JAWS, and NVDA reach content with alt text, the alt text is read aloud so people can better understand what's on the screen. Well-written, descriptive alt text dramatically reduces ambiguity and improves user experience.
This topic describes how to understand, write, and use effective alt text in Microsoft 365 products.
To help you with alt text, Microsoft 365 offers the Accessibility checker to review relevant visual content for alt text and get suggestions on improving content accessibility, an Automatic alt text generator, and a manual alt text editor.
Automatic alt text generation needs Microsoft 365 intelligent services. To turn this on:
Make sure to convey the content and the purpose of an image in a concise and unambiguous manner. The alt text shouldn’t be longer than a sentence or two—most of the time a few thoughtfully selected words will do. Consider what is important about an image. For example, important context might be the setting, the emotions on people's faces, the colors, or the relative sizes.
Do not repeat the surrounding textual content as alt text or use phrases referring to images, such as, "a graphic of" or "an image of." In the example below, the alt text is referring to the image and does not describe the content of the image sufficiently.
You can also add alt text as an argument to the IMAGE function either by using text in quotes or by using a cell reference that contains the text. For example, IMAGE("www.contoso.com/logo.jpg", "Contoso logo").
When dealing with objects that give detailed information, such as an infographic, use alt text to provide the information conveyed in the object. Describing a chart as ‘A bar chart showing sales over time,' for example, would not be useful to a blind person. Try to convey the insight; for example, ‘A bar chart showing sales over time. In July, sales for brand A surpassed sales for brand B and kept increasing throughout the year.’ Alt text should also clearly describe the beginning point, progress, and conclusion of flow charts.
Videos that don't explain their content require alt text to describe the visual experience, even if the user hears music, background sounds, and speech. Alt text should describe the content and purpose of the video.
Ideally, a video should contain a second audio track with a description of the video elements that are purely visual and not accessible to people with a visual disability.
The Microsoft 365 Accessibility Checker does not flag if a table is missing alt text. However, it is always a good practice to write a clear, descriptive, and concise alt text for a table.
Decorative objects add visual interest but aren’t informative (for example, stylistic borders). People using screen readers hear these are decorative so they know they aren’t missing any important information. To mark a visual as decorative, select the Mark as decorative checkbox in the Alt Text pane. The text entry field becomes grayed out.
Tip: If you export your document as a PDF, any visuals you have marked as decorative are automatically tagged as artifacts. They are then ignored by screen readers when navigating through PDFs.
If the Microsoft 365 Accessibility Checker doesn't flag an object when it's missing alt text, you don't have to write alt text for it. A slicer is an example of such an object.
For instructions on how to add alt text in Outlook, Word, Excel, and PowerPoint, go to Add alternative text to a shape, picture, chart, SmartArt graphic, or other object.
Note: If you have used Microsoft 365 for a while, you might have noticed that the Alt Text pane used to have two fields, Title and Description. Now we use a single Description field in most of our apps—it has been found that having a single field is easier and less confusing for both you as the author and also anyone using a screen reader to consume the content.
In Microsoft 365, alt text can be generated automatically. When you insert a picture, you might see a bar show up at the bottom of the picture with automatically generated alt text.
In Office 2019, alt text is not generated automatically when you insert an image. If you want to add automatic alt text, select the Generate a description for me button in the Alt Text pane. Depending on the content of the image, sometimes the feature gives you descriptive tags and sometimes you get full sentences.
If automatic alt text is generated, remember to review and edit it in the Alt Text pane and remove any comments added there such as "Description generated with high confidence."
Note: Before you can use automatic alt text, you might have to enable Microsoft 365 Intelligent Services in any Microsoft 365 product.
1. On the File tab, select Options and choose General.
2. Select Enable services under Microsoft 365 intelligent services.
Get additional resources to help you write effective alt text:
