What is Alt Text in Power BI?

Adding alt text to your Power BI visuals is one of the quickest ways to make your reports dramatically more useful and inclusive for your entire audience. It’s a small step that delivers a high impact, ensuring everyone can access and understand the insights you’re sharing. This article will walk you through exactly what alt text is, why it matters, and how to write effective descriptions for your Power BI visuals.

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What Exactly is Alt Text?

Alt text, short for "alternative text," is a written description of a non-text element on a screen, like an image or a chart. Its primary purpose is to provide context and meaning for screen-reading software used by people with visual impairments. When a screen reader encounters a visual element, it reads the alt text aloud, allowing the user to understand the information conveyed by the chart or image.

Think of it as a narrator for your data visualizations. A sighted user can look at a bar chart and instantly see which bar is highest. A user with a screen reader relies on your alt text to get that same core insight. Beyond its main accessibility function, alt text also provides a description if a visual fails to load for any reason, showing a text description in its place.

Why Alt Text is Crucial in Power BI Reporting

In the context of Power BI, alt text transforms your reports from exclusive visual displays into accessible information hubs. It’s not just a "nice-to-have" feature, it's a fundamental aspect of responsible and effective report design.

Making Data Accessible and Inclusive

The most important reason to use alt text is inclusivity. Data-driven decisions should be available to everyone in an organization, regardless of ability. Without alt text, a Power BI report full of brilliant charts and graphs is essentially a blank page to someone using a screen reader. By providing clear descriptions, you ensure that team members with visual impairments can participate fully, contribute their perspectives, and benefit from the same insights as their colleagues.

This is also a matter of compliance for many organizations. Global standards like the Web Content Accessibility Guidelines (WCAG) require digital content, including business intelligence reports, to be accessible. Implementing alt text is a critical step toward meeting these standards.

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Improving Clarity for Everyone

The benefits of good alt text extend beyond users with screen readers. A well-written description serves as a concise summary of a visual's main point. This can help all users, especially those less familiar with the data, to quickly grasp the key takeaway without having to interpret the chart from scratch. When a manager is scanning a report for the bottom line, a clear alt text summary can reinforce the primary message of a visual instantly.

How to Add Alt Text in Power BI Desktop

Adding alt text to your Power BI visuals is incredibly simple. The feature is built directly into the formatting options for almost every object you can place on a report canvas.

Follow these steps:

1. Select the Visual: Click on the chart, graph, shape, or image you want to add alt text to.
2. Open the Format Pane: On the right-hand side of the screen, click the "Format your visual" icon, which looks like a paintbrush.
3. Expand the "General" Section: In the list of formatting options, click on "General" to expand it.
4. Find the "Alt Text" Box: Scroll down within the General section until you see the "Alt Text" field.
5. Write Your Description: Click inside the text box and type your descriptive text. The text is saved automatically as you type.

That's it! Your visual now has alt text that a screen reader will detect and read aloud. You can follow this process for bar charts, line charts, pie charts, maps, KPIs, images, and more.

Best Practices for Writing Effective Alt Text

Simply adding alt text isn't enough, the quality of the description determines its usefulness. The goal is to convey the same insight a sighted user would get from a brief glance. Here are some best practices to follow.

1. Be Specific and Concise

Avoid generic descriptions. Your alt text should be efficient and get straight to the point. Tell the user what type of chart it is and what data it shows.

• Instead of: "A bar chart of sales."
• Try this: "Vertical bar chart showing sales revenue by country. The United States has the highest revenue at $4.5M, followed by Canada at $2.1M."

2. Focus on the Insight, Not Just the Appearance

The most valuable service your alt text can provide is communicating the main takeaway of the visual. What is the story the data is telling? What conclusion should the user draw?

• Instead of: "Line chart with a red and blue line."
• Try this: "Line chart of monthly website traffic from 2022 to 2023. Organic traffic, shown in blue, shows a steady increase, while paid traffic, in red, spiked in November 2023."

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3. Skip Redundancy

There's no need to start your alt text with phrases like "Image of..." or "Chart of..." Screen readers announce the type of element before reading the alt text, so including it is repetitive. For example, a screen reader would say "Chart," and then read your alt text.

• Instead of: "A picture of a pie chart showing product distribution."
• Try this: "Pie chart showing market share by product. Product A holds the majority at 55%, with Product B at 30% and Product C at 15%."

4. Keep the Context in Mind

Remember that each visual is part of a larger report. Your alt text should be helpful on its own but also make sense within the narrative of the page. If the title of your report page is "Q4 Sales Performance Overview," your alt text for a chart on that page should connect back to that theme. For example, if the visual sits under a heading that says "Top Performing Regions," your alt text doesn't need to re-state that information.

Using DAX for Dynamic Alt Text

For a more advanced and powerful approach, you can use DAX (Data Analysis Expressions) to create dynamic alt text that updates based on user selections and filters. This ensures your descriptions are always relevant to what is currently displayed on the screen.

Here’s how you can set it up:

1. Create a New Measure

First, create a new DAX measure that will generate the text string for your alt text. For example, let's say you have a chart showing total sales by category, and you want the alt text to update when a user filters by year.

You could write a measure like this:

AltText Sales by Category = 
VAR SelectedYear = SELECTEDVALUE('Calendar'[Year], "all years")
VAR TopCategory = 
    CALCULATE(
        SELECTEDVALUE('Products'[Category]),
        TOPN(1, ALLSELECTED('Products'[Category]), [Total Sales])
    )
RETURN
    "Bar chart showing total sales by product category for " & SelectedYear & ". The top performing category was " & TopCategory & "."

This measure identifies the selected year (or defaults to "all years") and finds the top-performing category based on the current filter context.

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2. Apply the Measure to the Alt Text Field

Next, apply this newly created DAX measure to your visual's alt text property.

1. Select the visual.
2. Go to the "Format visual" > "General" > "Alt Text" section.
3. To the right of the text box, you’ll see an fx symbol for "Conditional formatting." Click it.
4. In the dialog box that appears, set the "Format style" to "Field value."
5. Under "What field should we base this on?," select the DAX measure you just created (e.g., AltText Sales by Category).
6. Click "OK."

Now, when a user interacts with the report and filters by a specific year, the alt text will dynamically update to reflect their selection, providing a highly relevant and accessible experience.

How to Test Your Report's Accessibility

After implementing alt text, it's a good practice to test it. The easiest way to do this is by using a built-in screen reader like Windows Narrator (available on all Windows devices) or VoiceOver (on Macs). Turn it on and try navigating your report using only the keyboard (specifically the Tab key to move between visuals). Listen to how the descriptions sound. Is the information clear? Does it make sense? This simple test can reveal gaps in your descriptions and help you refine them for a better user experience.

Final Thoughts

Implementing alt text in your Power BI dashboards is a fundamental practice for creating inclusive, clear, and professional-grade reports. It ensures everyone on your team has access to the same information and transforms your visuals into truly accessible data stories. By following these steps and best practices, you can make your reporting more effective and user-friendly for your entire audience.

Starting with a clean slate makes building clear and accessible reports much easier. Often, the hardest part of business intelligence isn't just formatting visuals but wrangling the data across a dozen platforms just to get started. At Graphed , we simplify this first, crucial step. Instead of forcing you to learn a complex tool, we allow you to connect your data sources and create insightful dashboards just by describing what you need in plain English. This lets you focus on the insights from the start, making the entire analytics process - from data connection to accessible reporting - faster and more intuitive for everyone on your team.