How to Synchronize Axis in Power BI

Creating a chart with two different scales can accidentally turn an insightful visual into a confusing one. If you’ve ever built a Power BI report comparing two metrics - like sales revenue and units sold - and watched one line dwarf the other, you know the feeling. This article will walk you through exactly how to synchronize your Y-axis in Power BI so your reports are clear, accurate, and easy to understand.

Why Synchronizing Axes Matters in Power BI

In data visualization, context is everything. When you place two sets of data on the same chart using a primary and secondary Y-axis, Power BI's default behavior is to auto-size each axis based on its own data range. This is usually fine, but it can create a misleading picture if the viewer doesn't pay close attention.

Imagine you're charting monthly sales revenue (ranging from $500,000 to $750,000) against the number of units sold (ranging from 1,000 to 1,500). The revenue axis might go from $0 to $1M, while the units axis goes from 0 to 2,000. On the chart, a small fluctuation in units sold might look as dramatic as a massive swing in revenue, simply because the scales are so different. This makes it difficult to grasp the true relationship between the two metrics at a glance.

Synchronizing the axes forces both scales to use the same minimum and maximum values. It establishes a common baseline, allowing for an apples-to-apples comparison of trends and performance.

How to Synchronize the Y-Axis in a Combo Chart

The most common scenario requiring axis alignment is the "Line and Clustered Column Chart," also known as a combo chart. Power BI doesn’t offer a one-click "synchronize" button for this, so you’ll need to do it manually. It’s a straightforward process once you know where to look.

Step 1: Set Up Your Combo Chart

First, build your basic combo chart. Let's use an example where we compare monthly Target Sales (a goal) with Actual Sales (the result). Both are currency values, but their ranges might be slightly different, which could distort the visual.

• Select the Line and clustered column chart from the Visualizations pane.
• Drag your date field (e.g., Month) to the X-axis field well.
• Drag your first metric (e.g., Actual Sales) to the Column Y-axis.
• Drag your second metric (e.g., Target Sales) to the Line Y-axis.

You'll now have a column chart for actual sales and a line chart overlaid for your sales target. You’ll notice two Y-axes on either side of the visual, each with its own scale.

Step 2: Find the Y-Axis Formatting Options

With your chart selected, navigate to the Format your visual pane (the icon that looks like a paintbrush right below the Visualizations list). This is where you'll control the appearance of your chart, including the axes.

1. Expand the Y-axis section. You will see two tabs at the top of this section: one for the Primary axis (your columns) and one for the Secondary axis (your line).
2. Take note of the Range values (Minimum and Maximum) for the Primary axis. Power BI will likely have these set to "Auto," but you can see the numbers it generated. Let's say it's 0 for the minimum and 80,000 for the maximum.

Step 3: Manually Set the Axis Ranges

Now, click on the Secondary Y-axis tab to switch to the formatting options for your line chart's axis.

1. In the Range section, you’ll again see fields for Minimum and Maximum.
2. Manually type in the same values you noted from the Primary axis. In our example, you would enter 0 for the Minimum and 80000 for the Maximum.

As soon as you enter the new values, you’ll see the secondary Y-axis on the right side of the chart update its scale. Now both axes run from 0 to 80,000, and your visual is perfectly synchronized. The relationship between your actual sales columns and target sales line is now visually accurate and easy to interpret.

To clean up the chart, you can toggle the Secondary Y-axis off, since its scale is now redundant. Just click the on/off slider for "Secondary Y-axis" to hide it, leaving you with a single, clean axis on the left.

A Quick Note on This Method

Manually setting the axis range is effective, but it is static. If your dataset updates and the sales values exceed the maximum you set (in our case, 80,000), parts of your chart will be cut off. You'll need to periodically check and reset the range if your data changes dramatically. A good practice is to set the maximum slightly higher than your current highest value to give it some room to grow (e.g., set it to 100,000).

For Automatic Syncing: Use Small Multiples

If your goal is to compare the same metric across different categories (like comparing sales across different regions or product lines), manually creating several separate charts and synchronizing their axes is tedious. Power BI provides a much better solution for this: Small Multiples.

Small Multiples automatically duplicates your chart for each item in a category, arranging them in a grid. The best part? Power BI automatically synchronizes the Y-axis across all of them.

How to Use Small Multiples

1. Start with a basic visual, like a standard Line chart.
2. Drag your time-based field (e.g., Date) to the X-axis and your main metric (e.g., Revenue) to the Y-axis.
3. Now, drag the field you want to compare by (e.g., Country or Product Category) into the Small multiples field well, located just below the Y-axis field.

Instantly, your single line chart will split into a grid of smaller line charts, one for each country or category. You can clearly see that the Y-axis scale is identical on every chart, making it incredibly easy to spot which segments are high-performing and which are lagging. It's the cleanest way to make synchronized comparisons without any manual adjustments.

Quick Tips & Final Checks

• Is a Second Axis Even Necessary? Before you build a combo chart, ask yourself if it's the right choice. If you're comparing two very different types of metrics (like Revenue in millions of dollars versus Click-Through Rate as a percentage), a second axis is perfectly valid. The goal isn't to compare direct values but to show correlation. In cases like this, you may not even want to synchronize the scales. Sometimes, two separate, clear visuals are better than one crowded one.
• Label Everything Clearly: Ensure your Axis titles, Chart title, and data labels are crystal clear. Don't make your audience guess what the solid line or blue bars represent. Explicit labeling removes ambiguity.
• When Your Secondary Axis Disappears: If you're in the Format pane and don't see the option for a secondary Y-axis, it's almost always because you haven't placed a measure in the Line Y-axis field well yet. Add a measure there, and the formatting options will appear.

Final Thoughts

By understanding how to manually adjust your chart axes or use features like Small Multiples, you can ensure your Power BI reports are not just visually appealing but also statistically honest. This helps your team make better decisions by removing the risk of misinterpretation that comes from unsynchronized scales.

Manually building, formatting, and synchronizing visuals in tools like Power BI is a common part of a data analyst's work, but it definitely takes time. At Graphed, we remove the friction by letting you use simple conversational language to build reports. Instead of finding formatting panes and manually entering numbers, you can just ask something like, "build a chart comparing revenue vs. profit by month for the last six months," and we instantly generate a clear, accurate visual for you - no tinkering required.