How to Add Multiple Trend Lines in Excel

Ever look at a sales chart and wonder if one product's growth is outpacing another, or if your website traffic trend is linear or exponential? Excel's trend lines can give you the answer, but the real power comes from comparing more than one at a time. This guide will show you exactly how to add and customize multiple trend lines to an Excel chart, helping you move from basic data plots to insightful analysis.

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Why Would You Need More Than One Trend Line?

Adding a single trend line is a great way to see the general direction of your data. Adding multiple trend lines, however, lets you perform more sophisticated comparisons and analyses directly on your chart. There are two primary reasons you'd want to do this:

• To Compare Trends Across Different Data Groups: This is the most common use case. For example, you might want to visualize and compare the sales growth of two different products, website traffic from two different marketing channels (like Google vs. Facebook), or the performance of two sales reps over the same period. Putting their trend lines on the same chart makes the comparison immediate and obvious.
• To Find the Best "Model" for a Single Data Set: Sometimes, a straight line (linear trend) doesn't accurately represent your data. Your growth might be accelerating (exponential) or have predictable peaks and valleys (polynomial). By adding several types of trend lines to the same data set, you can visually determine which model best fits the story your numbers are telling.

Before you can do either, you need to make sure your data is set up correctly.

Start with Properly Structured Data

Excel is powerful, but it relies on neat and tidy data to work its magic. Before building any charts, organize your information into a simple tabular format. Your first column should almost always be your independent variable - usually a time-based series like dates, months, or quarters. Subsequent columns should contain your dependent variables - the metrics you want to measure, like sales, website sessions, or subscriber counts.

Imagine you're an e-commerce manager comparing the monthly unit sales for two new products: the "SuperWidget" and the "MegaGadget." Your data should look like this:

Table 1: Monthly Unit Sales

With this simple, clean structure, you're ready to create a chart and start adding your trend lines.

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Method 1: Adding Trend Lines for Multiple Data Series

Let's use the product sales data from above to compare the growth trajectories of the SuperWidget and the MegaGadget. The goal is to put a unique trend line on each product's sales data to see which one has a steeper growth curve.

Step 1: Create Your Chart

1. Highlight the entire data range, including the headers (in our example, from cell A1 to C7).
2. Go to the Insert tab on Excel's ribbon.
3. In the Charts group, click on Insert Line or Area Chart and select the first option under 2-D Line.

Excel will instantly generate a line chart showing two lines: one for SuperWidget Sales (blue by default) and one for MegaGadget Sales (orange by default).

Step 2: Add a Trend Line to the First Data Series

1. Single-click directly on the blue line on your chart (the one representing SuperWidget Sales). You'll see small circles appear on the data points to confirm it's selected.
2. Right-click on the selected line.
3. From the context menu that appears, choose Add Trendline...

Excel will immediately add a dotted trend line to the chart for the SuperWidget series and open the Format Trendline pane on the right side of your screen. By default, Excel adds a Linear trend line, which is perfect for this comparison.

Step 3: Add a Trend Line to the Second Data Series

Adding the second trend line is just as easy. You simply repeat the process for the other data series.

1. Single-click directly on the orange line on your chart (for MegaGadget Sales). Make sure the circles appear on its data points.
2. Right-click on the selected orange line.
3. From the context menu, choose Add Trendline...

Excel now adds a second dotted trend line, this time tracking the trend for MegaGadget sales. You now have a clear, side-by-side visual comparison. From the chart, you can instantly see that the MegaGadget's trend line is steeper, indicating it has a faster growth rate than the SuperWidget over this period.

Method 2: Adding Multiple Trend Models to a Single Data Series

What if you only have one data series, but you aren't sure if a straight-line trend is telling the whole story? For example, your website traffic might be accelerating. In this case, comparing several different trend line types on the same data can reveal deeper insights.

The catch? Excel won't let you add more than one trend line to a single data series. But we can get around this with a clever trick: duplicating the data to trick Excel into thinking we have two separate series.

Let's use this sample data for an email marketing campaign's daily subscriber growth:

Table 2: Daily Email Subscribers

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Step 1: Create a "Ghost" Data Series

Because Excel won't let us stack trend lines on the same data series, we'll duplicate our New Subscribers data. Simply copy the New Subscribers column and paste it into the next empty column. Call this new column "Ghost Subscribers" or something similar so you can keep track.

Your table should now look like this:

Step 2: Create a Chart with Both Series

Just like before, create a line or scatter chart using all three columns. Your chart will look like it only has one line, because both the "New Subscribers" and "Ghost Subscribers" lines are identical and sitting right on top of each other.

Step 3: Add the First Trend Line (Linear)

1. Click on the line in the chart (you'll be selecting both series at once initially, so just click again to select one of them).
2. Right-click and select Add Trendline... The Format Trendline pane will open.
3. Leave the type as Linear.
4. Scroll down in the pane and check the box that says Display R-squared value on chart.

The R-squared value is a statistical measure of how well the data fits the trend line. A value closer to 1.0 means a better fit. This number will be our guide for figuring out which trend model is best.

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Step 4: Add the Second Trend Line (Exponential)

Now for the trick. Because we have our "ghost" data series, we can add a different trend line to it.

1. While your chart is still selected, go to the Chart Design tab. Click on Select Data. This brings up a box showing the data sources for your chart.
2. Select the second series on your chart and add a trendline to it. A little tough to select, but hovering over the line should do it. Right-click your duplicated line. Then click Add Trendline...
3. This time in the Format Trendline pane select Exponential.
4. Just like before, be sure to check the box for Display R-squared value on chart.

Now you'll have two lines and two R-squared values on your chart. In the case of our accelerating subscriber data, the R-squared for the Exponential trend will likely be higher (e.g., 0.99) than the Linear trend (e.g., 0.92). This tells you definitively that an exponential model is a better representation of your subscriber growth.

<div class="tip" style="text-align: center, border: 1px dashed black, background-color: #f7fcfe, padding: 25px, margin-top: 25px,"> <h5 style="margin-top: 10px,">Common Trend Line Types in Excel and What They Mean (In Plain English)</h5> <p align="left"><b>Linear:</b> The most common type. Use this when your data increases or decreases at a steady, constant rate. Think straight-line growth.</p> <p align="left"><b>Logarithmic:</b> Good for data that initially grows rapidly and then levels off over time. Think of product adoption or initial campaign engagement.</p> <p align="left"><b>Exponential:</b> The opposite of logarithmic. Use this when your data grows slowly at first and then starts accelerating rapidly. Useful for modeling viral growth.</p> <p align="left"><b>Polynomial:</b> A flexible model that is great for data sets with multiple peaks and valleys, like seasonal sales data. Increase the "Order" in the trend line pane to make the line curvier and better fit the fluctuations.</p> </div>

Quick Tips for Customizing Your Trend Lines

Once your trend lines are in place, you may want to clean them up for better readability.

• Formatting: Click on a trend line to open the pane where you can change the color, thickness, and the dash type to help each trend line stand out. It's a good idea to make each trend line the same color as the data set it represents.
• Forecasting: Use the options in the Format Trendline pane to project your trends into the future.
• Labels: Excel doesn't automatically add labels to trend lines, but it's a good idea to manually add them. Be sure to indicate the data set and type of trend line (e.g., "Linear - SuperWidget Sales") so everyone understands what your chart is showing.

Final Thoughts

Adding multiple trend lines in Excel isn't just a click of a button, it's an effective way to unlock comparative analysis. Whether you're comparing the growth of different data sets or finding the best model for your data set, these techniques elevate your charts from simple visuals to decision-making tools.

Manual trend line comparisons in Excel can be invaluable, especially when your data covers different places or formats. At Graphed , we help you skip the spreadsheet hassle with automated updates that ensure you're always ready to act on insights promptly.