How to Overlap Graphs in Excel

Want to display two different sets of data on a single, easy-to-read Excel chart? You can do this by creating an overlapping graph, which combines multiple chart types into one powerful visual. This article will show you exactly how to build combination charts in Excel to compare different data series and tell a more compelling story with your numbers.

Why Overlap Graphs in Excel?

Overlapping graphs, often called "combo charts," are excellent for showing the relationship between two or more different types of data over the same period. While a standard bar chart can show monthly sales, it can't easily show how your ad spend influenced those sales. A combo chart can.

Common scenarios where overlapping graphs are incredibly useful include:

• Revenue vs. Units Sold: You can show total revenue growth with bars and the number of individual units sold with a line. This helps you see if you're growing by selling more items or by selling more expensive items.
• Website Traffic vs. Conversion Rate: Display website sessions as columns and overlay the conversion rate as a line. This quickly reveals if a traffic spike actually led to a proportional increase in conversions.
• Actual vs. Target Performance: Plot actual sales results as bars against a target goal represented by a simple line. At a glance, your team can see which months they hit the target and by how much.
• Rainfall vs. Temperature: A classic example where you can compare two completely different metrics (e.g., millimeters of rain vs. degrees Celsius) over a period, like a year.

The goal is to provide context. By layering data, you help people connect the dots between different metrics without having to jump between multiple separate charts, making your report clearer and more insightful.

The Best Way: Creating a Combination Chart

The easiest and most reliable way to overlap graphs is by using Excel’s built-in Combo chart feature. It properly aligns the data points, gives you control over the axes, and creates a professional-looking chart in just a few clicks. Let's walk through an example using monthly advertising spend and the number of new customers acquired.

Step 1: Set Up & Select Your Data

First, organize your data in a clean table. Your first column should contain your labels (like dates or categories), and subsequent columns should contain the numeric data you want to plot. Make sure each column has a clear header.

For our example, the table looks like this:

Once your data is ready, click and drag to select the entire table, including the headers.

Step 2: Insert a Recommended Chart

With your data selected, navigate to the Insert tab on the Excel ribbon. Click on Recommended Charts. Excel will analyze your data and suggest a few options. Most of the time, the "Clustered Column" is a good starting point.

Select the basic "Clustered Column" chart and click OK. You'll now have a bar chart with two sets of bars for each month - one for "Ad Spend ($)" and one for "New Customers."

Right away, you can see a problem. The 'Ad Spend' values are in the thousands, while 'New Customers' are in the dozens. This makes the 'New Customers' bars look tiny and almost invisible, hiding any trends. This is the exact problem a combo chart solves.

Step 3: Change a Series to Create a Combo Chart

Now, let's turn this into a combination chart. Right-click on one of the data series on the chart. It can be tricky to click on the tiny "New Customers" bars, so you can right-click the larger "Ad Spend" bars if that's easier.

In the menu that appears, click on Change Series Chart Type...

Step 4: Configure the Combo Chart and Add a Secondary Axis

This opens the "Change Chart Type" window. At the bottom, you'll see a section where you can customize the chart type for each data series.

This is where the magic happens:

1. Find the series you want to change - in our case, "New Customers."
2. Click the dropdown menu next to it and change its chart type from "Clustered Column" to Line. You'll see the preview update immediately.
3. Now for the most important step: To fix the scale problem, check the "Secondary Axis" box to the right of the "New Customers" series.

The Secondary Axis creates a new vertical axis on the right side of the chart that is scaled specifically for the "New Customers" data. The original vertical axis on the left remains scaled for the "Ad Spend" data. Now, both the bars and the line are clearly visible and scaled appropriately, showing the relationship between spend and acquisition perfectly.

Click OK to apply your changes.

Step 5: Format and Tidy Up Your Chart

Your combo chart is technically complete, but it's important to make it clean and understandable.

• Give it a clear title: Something like "Ad Spend vs. New Customers Acquired by Month."
• Label Your Axes: Click the "+" icon next to your chart and check the "Axis Titles" box. Label the left axis "Ad Spend ($)", the right axis "Number of New Customers," and the bottom axis "Month."
• Adjust Colors: If you don't like the default colors, right-click a series (like the bars) and select "Format Data Series." You can change the fill color to match your company's branding.

Manual Method: Overlapping Two Separate Charts

For more creative or unconventional combinations that Excel's Combo chart feature doesn't support, you can manually layer two charts. This technique gives you complete freedom but is also much more fiddly to manage.

Use this method when you want to overlay a scatter plot over a bar chart to show correlation or when you need exceptional control over the position and size of each chart element.

How to Do It

1. Create your primary chart: Build a standard bar chart using only your primary data series (e.g., "Ad Spend").
2. Make the background transparent: Right-click the chart area and select "Format Chart Area." Under "Fill," choose "No fill." Under "Border," choose "No line."
3. Create your secondary chart: Follow the same process to create a second, separate chart with your other data series (e.g., a line chart for "New Customers").
4. Make this chart transparent, too: Just like before, set its "Fill" and "Border" to none.
5. Align the charts: Carefully drag the second chart on top of the first. You'll need to resize and position them until the axes and gridlines are perfectly aligned. Hold the ALT key while dragging for more precise snapping.
6. Group them together: Once aligned, hold CTRL (or Command on Mac) and click on both charts to select them. Right-click and choose Group -> Group. This locks them together so you can move and resize them as one object.

While powerful, this manual approach is fragile. If you update the data, you may have to realign the charts. For most cases, the built-in Combo Chart feature is the better choice.

Best Practices for Creating Clear Overlapping Graphs

• Don’t Overcomplicate: Combo charts are best for two, or at most three, different data series. Adding more turns your chart into visual noise. Simple is almost always better.
• Choose Compatible Chart Types: Columns and lines are a classic, effective pairing. Area charts and line charts can also work well. Avoid using two types of columns or two types of bars, as one will likely hide the other.
• Label Everything: When using a secondary axis, it's essential that your audience understands what each axis represents. Clearly label both the left and right vertical axes. A descriptive title and a clear legend are non-negotiable.
• Use Contrasting Colors: Pick colors that are easy to distinguish. A dark blue for the bars and a bright orange or green for the line will help each series stand out, improving readability.
• Be Cautious with the Secondary Axis: While useful, a secondary axis can be misleading. Because the two scales are independent, you can make trends look more or less dramatic by changing the max/min values of the axes. Always ensure your scales start from zero if possible and represent the data honestly.

Final Thoughts

Creating overlapping graphs in Excel, especially with the user-friendly Combo Chart tool, is a powerful skill for anyone working with data. It transforms a simple spreadsheet into a professional report that uncovers relationships and contextualizes performance in a way a single chart never could.

However, building these reports in Excel often starts with manually exporting CSVs from different platforms, cleaning the data, and then styling the chart. We built Graphed to eliminate that repetitive work. By connecting directly to your tools like Google Analytics, Shopify, or Facebook Ads, you can skip the spreadsheet altogether. Simply ask in plain English, "show me a chart comparing Facebook Ads spend vs Shopify sales for the last 90 days," and our AI Data Analyst will instantly generate a live dashboard that updates automatically, so you can spend your time finding insights, not wrestling with chart settings.