How to Use a Sankey Chart in Power BI

Sankey charts are one of the most effective ways to tell a story about how data flows from one point to another. They bring processes and paths to life, turning a static table of numbers into a clear, intuitive visual narrative. This tutorial will walk you through exactly what a Sankey chart is, why it’s so useful, and how to build one step-by-step in Power BI.

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What Is a Sankey Chart?

A Sankey chart is a type of flow diagram where the width of the arrows or bands is proportional to the quantity of the flow. In simple terms, it visualizes the movement of something - like users, money, or materials - from a source to a destination.

Imagine you're tracking website visitors. A Sankey chart can show you:

• All your traffic sources on the left side (like Google, Facebook, and Email).
• All your important landing pages in the middle (like your Homepage, Pricing page, and a Blog post).
• Your conversion goals on the right side (like "Signed Up" or "Made a Purchase").

The chart draws connecting bands between these stages. A thick band from "Google" to your "Homepage" immediately tells you that's a primary user path. A thin band from your "Blog post" to "Made a Purchase" shows that path isn't a major driver of sales. The flow and its magnitude are instantly clear, in a way a pie chart or a bar graph could never demonstrate.

The core components of a Sankey chart are:

• Nodes: These are the categories or stages in your process, represented as vertical rectangular bars (e.g., 'Facebook Ads', 'Homepage').
• Links (or flows): These are the colored bands that connect the nodes, showing the path and volume of the flow between them.

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Why Use a Sankey Chart Instead of Other Visuals?

Sankey charts excel where other visuals fall short. They unpack complex systems and reveal relationships that would otherwise be hidden in rows and columns of data. Here are a few compelling reasons to use them in your Power BI reports.

• Visualize Multi-Step Journeys: They are perfect for analyzing funnels, user behavior, and customer journeys. You can easily map how users navigate from ad click to landing page to checkout and identify key drop-off points along the way.
• Illustrate Contributions and Allocations: Need to show how a marketing budget is allocated across different channels and how those channels contribute to different outcomes like leads and sales? A Sankey chart makes complex budget breakdowns easy to digest.
• Identify Dominant Paths and Inefficiencies: The most significant paths visually dominate the chart, drawing immediate attention to what’s most important. Conversely, you can quickly spot bottlenecks or processes where resources are getting "stuck" or dropping off unexpectedly.
• Provide a Holistic View: Unlike a funnel chart that just shows drop-offs in a linear process, a Sankey can show how different sources contribute to multiple destinations, giving you a complete system-wide view of distribution.

Getting Started: Importing the Sankey Chart Visual

Sankey charts are a fantastic tool, but they aren't included in Power BI’s default set of visualizations. Don't worry, you can easily add one from AppSource, Microsoft's marketplace for custom visuals, for free.

Follow these quick steps:

1. Open your report in Power BI Desktop.
2. In the Visualizations pane, click the three-dot menu (...) at the bottom.
3. Select Get more visuals from the pop-up menu.
4. In the AppSource window that appears, use the search bar at the top right and type "Sankey".
5. You'll see a few options. The one named "Sankey" with the official "Microsoft Power BI Certified" checkmark is an excellent place to start.
6. Click on the visual you prefer, then click the blue Add button.

Once you’ve successfully added it, a new icon for the Sankey chart will appear in your Visualizations pane, ready to be used just like any other visual.

Building Your First Sankey Chart in Power BI (Step-by-Step)

Now for the fun part: building the chart. We’ll use a simple marketing example to track how visitors from different sources end up on different landing pages.

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Step 1: Prepare Your Data

The Sankey chart expects your data to be structured in a specific way. At a minimum, you need three columns:

• A Source column (where the flow starts).
• A Destination column (where the flow ends).
• A numeric Value column that "weights" the flow.

Let's say your data looks like this:

This simple table structure is all you need to get started.

Step 2: Add the Sankey Chart to the Report Canvas

Click on the new Sankey icon in your Visualizations pane. This will add a blank Sankey chart template to your Power BI report.

Step 3: Populate the Visual's Fields

With the blank Sankey chart selected, you’ll see the fields you need to populate in the Visualizations pane. Now, just drag and drop your data columns into the correct fields:

• Drag your SourceChannel column into the Source box.
• Drag your LandingPage column into the Destination box.
• Drag your Visitors column into the Weight box.

The moment you drop the final field, your Sankey chart will come to life on the canvas! You'll see nodes for your sources and destinations, with flows representing the number of visitors moving between them.

Step 4: Interpret the Chart

Instantly, you can see that "Google Search" is your biggest traffic driver to the "Homepage." You'll also notice the relative contributions of Facebook Ads and Email Campaigns. By hovering your mouse over any link or node, Power BI will give you the precise headcount for that specific flow.

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Customizing Your Sankey Chart for Greater Impact

Your basic Sankey is live, but you can enhance its readability and aesthetic with a few simple formatting tricks.

Formatting Options

Select your Sankey chart and navigate to the Format your visual tab (the paintbrush icon) in the Visualizations pane. Here are a few useful settings:

• Links: This section lets you customize the appearance of the flows. You can change the colors of individual links to make specific paths stand out. Try enabling "Conditional formatting" to automatically color flows based on their weight - for example, making larger flows darker.
• Data labels: Turn these on to display the numeric value directly on the flow itself, which can save your viewers from having to hover over each one.
• Nodes: Here you can adjust the appearance of the source and destination bars, changing their color or width.
• Scale Settings: This setting allows you to toggle logarithmic scaling. It can be useful if you have extremely disparate flow values (e.g., one flow is 1,000,000 and another is 100), as it helps visualize the smaller flows more clearly.

Common Pitfalls to Avoid

• Overcrowding the chart: If you have dozens of sources or destinations, your Sankey can quickly become an unreadable "spaghetti chart." To clean it up, consider grouping smaller categories into an "Other" category or using report filters in Power BI to focus on the most important flows.
• Building dead-end flows: To tell a complete story, make sure your chart balances. The total flowing out of the source nodes should ideally equal the total flowing into the destination nodes. If they don't, it might indicate you have incomplete data.

Final Thoughts

Sankey charts are a powerful addition to any Power BI dashboard, offering an insightful and visually compelling way to analyze processes and distributions. By importing the custom visual and structuring your data properly, you can move beyond standard bar charts to tell a much deeper story about how your business really works.

Of course, building the chart is only half the battle. The often-frustrating part is just getting clean data from Google Analytics, Facebook Ads, Shopify, and your other platforms connected and ready for analysis in the first place. This is why we built Graphed to help. We automate the connection to all your key data sources, letting you create dashboards and reports using simple language - so you can focus on finding insights, not wrestling with BI tool configurations.