How to Make a Double Line Graph in Excel

A double line graph is one of the most effective ways to compare two different trends over the same period. This article will walk you through exactly how to set up your data and create a clean, easy-to-read double line graph in Microsoft Excel, including a pro tip for when your data sets use completely different scales.

What is a Double Line Graph (and When Should You Use One)?

Simply put, a double line graph (or multiple line graph) is a chart that uses two lines to represent two different sets of data points. The horizontal x-axis typically represents a continuous progression of time (like days, months, or years), while the vertical y-axis represents a numerical value.

This type of chart is incredibly useful for visually comparing the performance of two related metrics. It allows you to instantly spot relationships, patterns, and divergences. You aren't just looking at two separate trends, you're seeing how they move together (or apart).

Here are a few common business scenarios where a double line graph is the perfect tool:

• Marketing: Comparing ad spend on Google Ads vs. Facebook Ads for the last quarter to see which platform corresponds with higher revenue.
• Sales: Tracking the number of new leads generated vs. the number of deals closed each month to see if you have a conversion bottleneck.
• E-commerce: Plotting total website traffic against total sales revenue over the past year to understand seasonality and the impact of traffic on sales.
• Product Management: Comparing new user sign-ups vs. user churn rate on a weekly basis to gauge product stickiness.

In each case, the goal is the same: to analyze the relationship between two changing variables over time.

Step-by-Step Guide to Making a Double Line Graph in Excel

Creating your chart is a straightforward process. The most important part is making sure your data is organized properly before you start. Let's build one from scratch.

For our example, we'll compare Monthly Marketing Spend against the Website Traffic it generated for the first half of the year.

Step 1: Set Up and Format Your Data

Good charts start with clean data. Before you even think about clicking the "Insert" button, organize your information in a simple table. Your table should have at least three columns:

• Column A: The time period (e.g., Day, Month, Year). This will be your x-axis.
• Column B: The first data series you want to plot (e.g., Marketing Spend).
• Column C: The second data series you want to plot (e.g., Website Traffic).

Make sure the column headers are descriptive, as Excel will use these to automatically create a legend for your chart. Here’s how our example data looks:

Your table should look something like this:

Step 2: Insert the Line Chart

With your data neatly organized, it’s time to create the chart.

1. Click and drag to highlight the entire data range, including the column headers (e.g., cells A1 through C7 in our example).
2. Go to the Insert tab on Excel’s ribbon.
3. In the Charts section, click on the icon that looks like a line graph (called "Insert Line or Area Chart").
4. A dropdown menu will appear. Under the "2-D Line" section, select the first option, called simply Line. You can also choose "Line with Markers," which shows the specific data points on each line.

Excel will instantly drop a basic double line graph onto your worksheet. It might look decent right away, but we can do a lot to make it clearer and more professional.

Step 3: Customize Your Chart Elements for Clarity

An untitled, unlabeled chart isn’t telling the full story. Let's add the necessary context to make it immediately understandable to anyone who sees it.

First, click anywhere on your new chart to select it. This will reveal two new tabs on the ribbon: Chart Design and Format.

• Add a Chart Title: Every chart needs a title. Click on the "Chart Title" text at the top of your graph and type something descriptive. For example: "Website Traffic vs. Marketing Spend - H1 2024". A good title should tell the viewer exactly what they are looking at.
• Add Axis Titles: People need to know what the numbers on the axes represent. In the Chart Design tab, click on Add Chart Element > Axis Titles. Add a "Primary Horizontal" title (e.g., "Month") and a "Primary Vertical" title (e.g., "Values"). This prevents any confusion.
• Improve the Legend: Excel automatically created a legend using your column headers. If the names are unclear, you can edit them. Right-click the chart, choose Select Data, and in the dialogue box, you can click on each series and hit "Edit" to change its name to something more specific.
• Customize the Lines: You can change the color, thickness, and style of each line to improve contrast. Right-click on the data line you want to change and select Format Data Series. A pane will open on the right where you can adjust colors, add markers for each data point, and more. This is particularly useful for making your charts easy to read when printed in black and white.

Pro Tip: Add a Secondary Axis for Data With Different Scales

What happens when you want to compare two metrics that are on completely different scales, like "Revenue" (in thousands of dollars) and "Conversion Rate" (a low percentage)? If you plot these on the same axis, the conversion rate will look like a flat line squished against the bottom, making it impossible to see any trends.

The solution is to add a secondary axis. Here's how:

1. Follow the steps above to create your double line graph as you normally would. You'll notice one line is barely visible.
2. Right-click on the flattened line (the one with the smaller data range) and select Format Data Series from the dropdown menu.
3. In the Format Data Series pane that appears on the right side of the screen, look for the Series Options section.
4. Select the option for Secondary Axis.

Instantly, Excel will add a second vertical axis on the right side of your chart, scaled specifically for that data series. The flattened line will re-scale itself against this new axis, and its trend will now be clearly visible.

Crucially, remember to add an axis title for this new secondary axis! You need to clearly label which line corresponds to which axis to prevent misinterpretation.

Common Mistakes and How to Avoid Them

Even a process this simple has a few common hiccups. Here are the ones to watch out for:

• Messed up Axes: Sometimes Excel misinterprets your data and plots your time period as a data series. If your months (or dates) are appearing in the legend, you have a problem. To fix this, right-click the chart, choose Select Data, and click the Switch Row/Column button. This usually corrects the issue.
• Wrong Chart Type: It can be tempting to choose another chart type. For comparing two trends over time, a line graph is almost always the right choice. A bar chart can also work, but becomes cluttered. A pie chart is definitely wrong for this type of data analysis.
• Unclear Labels: This is the biggest offense. Without a clear chart title, descriptive axis titles, and a visible legend, your graph is useless. Don't make people guess what they are looking at. Spend the extra 30 seconds to label everything properly.
• Misleading Scale: By default, Excel does a good job of setting the vertical axis range. However, sometimes people manually change the axis to start at a value other than zero to exaggerate small changes. Be cautious about this — while sometimes justified, it can often be misleading.

Final Thoughts

Creating a double line graph in Excel is a vital skill for anyone who needs to report on business data. By organizing your data correctly and taking a few moments to customize titles and labels for clarity, you can turn a basic spreadsheet into a powerful visual tool for comparing trends and discovering valuable insights.

As helpful as Excel is, spending your Monday mornings exporting CSVs and manually assembling these charts from scratch every single week can become a major drain on your time. Instead of rebuilding reports repeatedly, we designed Graphed to connect directly to your data sources like Google Analytics, Shopify, or your CRM. You can ask for a dashboard in plain English — like "create a chart comparing Facebook Ads spend vs revenue by campaign" — and get a live, real-time dashboard that automatically stays up-to-date, freeing you to focus on strategy instead of spreadsheet wrangling.