How to Add Tooltip to Matrix in Power BI

A Power BI matrix is great for summarizing data, but its dense format can hide valuable details. If you want to show your stakeholders the "why" behind the numbers without cluttering your report, adding a custom tooltip is a game-changer. This guide will walk you through exactly how to add rich, informative tooltips to your matrix, turning it from a static table into an interactive analysis tool.

What Are Tooltips and Why Use Them in a Matrix?

Think of a tooltip as a small pop-up window that appears when you hover your mouse over a specific data point. By default, Power BI matrices show a basic tooltip that simply lists the row, column, and value of the cell you're hovering over. It’s functional but not very insightful.

A custom tooltip replaces that default box with a mini visualization you design yourself. This is incredibly powerful for matrix visuals for a few key reasons:

• Provide Context Without Clutter: Your main matrix can show high-level numbers, like total sales per region. The tooltip can then reveal the next layer of detail, such as the top-selling products or sales performance over time for that specific region - all without adding more visuals to your crowded report canvas.
• Tell a Quick Story: Instead of just showing a number, a tooltip can show a trend. For example, hovering over a quarterly sales figure for a product could pop up a small line chart showing the monthly sales trend for that quarter.
• Enhance User Experience: Interactive elements make reports more engaging. Custom tooltips encourage users to explore the data, leading them to discover insights they might have otherwise missed.

Imagine you're a sales manager looking at a matrix of Q4 sales by salesperson. With a standard tooltip, hovering over Sarah's $150,000 sales figure just tells you "Salesperson: Sarah, Sales: $150,000." With a custom tooltip, that same hover action could reveal a pie chart of her sales by product category and a list of her top three deals - instant context, zero clutter.

The Easiest Method: Creating a Report Page Tooltip

The most common and flexible way to create a custom tooltip is by designing a separate report page that acts as your tooltip template. Power BI then intelligently filters this page based on the matrix cell you're hovering over.

Here’s the step-by-step process.

Step 1: Create a New Report Page

First, you need a dedicated canvas for your tooltip design. In Power BI Desktop, click the yellow '+' icon at the bottom of the screen to add a new page. It’s a good practice to give it a descriptive name. Right-click the new page tab and rename it to something like "Sales Details Tooltip." This makes it easier to find later.

Step 2: Configure the Page for Tooltip Use

This is the most important step for making the magic happen. A regular report page is too big to be a tooltip, so you need to change its settings.

1. Make sure you don't have any visuals selected. Click on the gray area of the new report page canvas.
2. Go to the Format pane on the right-hand side (the paintbrush icon).
3. Expand the Page information section. Toggle the switch for "Allow use as tooltip" to On.
4. Next, expand the Canvas settings section just below. Under Type, select "Tooltip" from the dropdown menu.

You'll see the page canvas shrink dramatically. This small canvas is where you'll build your tooltip visual. While the default size works well, you can adjust the height and width here if needed.

Step 3: Design Your Tooltip Visual

Now for the fun part: deciding what information you want to show in the pop-up. You can add any visuals you want to this small canvas - a bar chart, a donut chart, a card, or even multiple visuals.

Let's continue with our sales example. We have a main report page with a matrix showing Total Sales by Sales Region.

1. On your "Sales Details Tooltip" page, add a donut chart.
2. From your Fields pane, drag Product Category to the Legend well and Total Sales to the Values well.
3. You could also add a card visual and drag the Profit Margin measure into it to show the profitability of each region at a glance.

You’ll notice that these visuals currently show data for your entire company. Don't worry, that's normal. Once we link this page to the matrix, Power BI will automatically filter it based on whatever cell you hover the cursor over.

Step 4: Connect the Tooltip to Your Matrix Visual

With your tooltip page designed, the last step is to tell your main matrix to use it.

1. Navigate back to your main report page that contains the matrix visual.
2. Click on the matrix to select it.
3. In the Format visual pane, click on the General tab.
4. Expand the Tooltips section.
5. Click the dropdown menu for Type and select Report page.
6. A new dropdown menu named Page will appear. Select your newly created tooltip page ("Sales Details Tooltip").

Step 5: Test It!

That's it! Hover your mouse over any of the value cells in your matrix. Instead of the boring default tooltip, you should see your custom-designed donut chart and card pop up, showing you a filtered view of the data for that specific region. Hover over the "East" region, and you'll see a breakdown of products sold in the East. Hover over "West," and the tooltip will instantly update to show data for the West.

Going Further: Measure-Driven Tooltips for Different Columns

What if your matrix has multiple value columns, like "Total Sales" and "Total Units," and you want to show a different tooltip for each column? You can accomplish this with a simple DAX measure that dynamically tells Power BI which tooltip page to show.

The Scenario

Imagine your matrix has Country on the rows, and two measures as values: Total Revenue and Transaction Count. You want hovering over the Revenue column to show a tooltip with a profit breakdown, while hovering over the Transaction Count column shows a tooltip breaking down transactions by new vs. returning customers.

Step 1: Create Two Separate Tooltip Pages

First, follow the steps from the previous section to create two distinct tooltip pages:

• One named "Revenue Details" with a visual showing profit by product category.
• A second one named "Transaction Details" with a visual showing transaction count by customer type.

Make sure you go through all the page setup steps - enabling "Allow use as tooltip" and setting the canvas type to "Tooltip" for both pages.

Step 2: Write the DAX 'Selector' Measure

Now, we need a DAX measure that acts like a traffic controller, directing Power BI to the correct tooltip page. Click on "New measure" in the Home ribbon and enter the following formula:

Tooltip Selector = 
SWITCH(
    TRUE(),
    SELECTEDMEASURENAME() = "Total Revenue", "Revenue Details",
    SELECTEDMEASURENAME() = "Transaction Count", "Transaction Details"
)

Here’s a breakdown of this simple but powerful formula:

• SWITCH(TRUE(), ...) tests a series of conditions.
• SELECTEDMEASURENAME() is a DAX function that returns the name of the measure currently being evaluated in a visual's context (i.e., the one you're hovering over!).
• The formula checks if the name of the hovered measure is "Total Revenue" and, if so, returns the text "Revenue Details" - the exact name of our first tooltip page. If it's "Transaction Count," it returns "Transaction Details." It must match perfectly, including spaces and capitalization.

Step 3: Connect Your Matrix Using the DAX Measure

Last, let's link our matrix to this new measure.

1. Go back to your main report page and select your matrix.
2. In the Format visual > General > Tooltips section, set the Type to Report page (just like before).
3. This time, instead of picking a static page from the Page dropdown, click the small fx (Conditional formatting) button next to it.
4. In the window that appears:
5. Click OK.

Now when you hover over the Total Revenue column in your matrix, Power BI uses the measure to evaluate, gets back the text "Revenue Details," and shows you the Revenue Details tooltip page. Hover over the Transaction Count column and it shows you the Transaction Details tooltip. This technique lets you create highly contextual and dynamic reporting experiences with just one visual.

Best Practices for Effective Tooltips

To ensure your tooltips are useful and not overwhelming, here are some practices to keep in mind:

• <em>Keep It Simple:</em> A tooltip is meant to be concise. The goal is to provide quick context, not to create a mini dashboard within a tooltip. So, stick to one or two visuals that tell a clear story and reserve in-depth information for your main report.
• <em>Mind Your Size:</em> The default tooltip size is generally good, but if the text or visuals are hard to read or out of sync, make sure it's big enough to be readable without overpowering the underlying matrix.
• <em>Performance Matters:</em> If you pack too many calculations or visuals on your tooltip page, it can slow down the performance of your report every hover. The calculations that filter your visuals happen instantly, so keeping the design lightweight is crucial.
• <em>Be Clear in Your Tooltips:</em> If you have multiple tooltip pages, like in our DAX example, make sure to name them clearly so you and stakeholders can easily tell them apart when accessing them.

Final Thoughts

Tooltip functionality in Power BI matrices allows for an enriched user experience by providing deeper context without sacrificing cleanliness. By taking the time to create a report page tooltip, you elevate your reports from a static display of information to an interactive analysis tool.

Focusing on clear, concise context is the ultimate goal of any data visualization. Whether you are creating tooltips in Power BI or using another data platform, leveraging this capability can enhance the functionality of your reports to meet the needs of your team or your audience.

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