How to Add Line to Scatter Plot in Excel (3 Practical Examples)

In this tutorial, I am going to share with you 3 practical examples of how to add lines to an Excel scatter plot. Lines may be needed to show a threshold or limit within your data, and are very useful in statistical analysis. Using lines properly can be very helpful in representing data.

To begin with, generate a scatter plot with the data set provided below. Once you have your scatter plot ready, you’ll be ready to follow along.

Example 1 – Add a Vertical Line to the Scatter Plot

Let’s add a vertical line to the following data set, which has an X column and a Y column.

Steps:

Right-click on the scatter chart and click on Select Data.

In the Select Data Source window, click on Add.

In the Edit Series window, set Vertical Line as the Series name.
Select cell B8 as Series X values and cell C8 as Series Y values.

Press OK and this will generate a new data point called Vertical Line.

Keeping the orange data point selected, go to Chart Design > Add Chart Element > Error Bars > Percentage.

A horizontal and a vertical line appear around the selected data point.

Right-click on the horizontal line and select Format Error Bars.

In the new window on the right side, set the horizontal line Percentage value to 0.

As before, right-click on the vertical line of the orange point.
In the Format Error Bars window, set the direction to Minus.

In the Error Amount option, set the Percentage value to 100%.

You now have a vertical line through your desired data point.

Example 2 – Add a Horizontal Line to the Scatter Plot

The first few steps of this method are exactly the same as the previous method. This time we will add a horizontal line to the scatter plot, again using the Error Bars option. We’ll also format the line to make it more visible.

Steps:

Just as we did previously, right-click on the vertical line and select Format Error Bars.

Again, set the Percentage value to 0 and press Enter.

Right-click on the horizontal line and go to Format Error Bars.
Set the direction to Minus.

Set the Percentage value to 100%.
Go to the Fill and Line options.

Set the color to Red and the width to 1 pt.

You now have a formatted horizontal line.

Example 3 – Adding a Slope Line to the Scatter Plot

In the previous two methods, we used only one point from our dataset to add a line to the scatter plot. Now, we are going to use two points to add a sloping line. The slope lines are very important for regression analysis.

Steps:

Right-click on the scatter plot and choose Select Data.

In the new Select Data Source window, click on Add.

In the Edit Series window, enter the series name Slope Line.
For the series X values, hold Ctrl and select cells B5 and B8.
For series Y values, hold Ctrl and select cells C5 and C8.
Simply press OK.

Now we have a new data point named Slope Line.

Select the two data points and right-click.
Select Change Series Chart Type.

In the new window that opens, go to the Combo option.
Click the dropdown arrow beside the Slope Line option.
From the dropdown options, select the icon with the name Scatter with Straight Lines.
Press OK.