Often you may have one or more missing values in a series in Google Sheets that you’d like to fill in.

The following step-by-step example shows how to interpolate missing values in practice.

**Step 1: Create the Data**

First, let’s create a dataset in Google Sheets that contains some missing values:

**Step 2: Calculate the Step Value **

Next, we will use the following formula to determine what step value to use to fill in the missing data:

Step= (End – Start) / (#Missing observations + 1)

For this example, we would calculate the step value as:

Step = (35 – 20) / (4 – 1) = **3**

We can type the following formula into cell **D1** to automatically calculate this value:

=(A13-A8)/(COUNTBLANK(A9:A12)+1)

The following screenshot shows how to use this formula in practice:

**Step 3: Interpolate the Missing Values**

Next, we need to add the step value to the missing values, starting with the first missing value:

We can then drag and fill this formula down to each remaining blank cell:

**Step 4: Visualize the Interpolated Values**

Lastly, we can create a line chart to see if the interpolated values seem to fit the dataset well.

To do so, highlight cells **A2:A21**, then click the **Insert** tab, then click **Chart**.

In the **Chart editor** panel that appears on the right side of the screen, choose **Line chart** as the **Chart type**.

The following line chart will appear:

The interpolated values seem to fit the trend of the dataset well.

**Additional Resource**

The following tutorials explain how to perform other common tasks in Google Sheets:

How to Add Multiple Trendlines to Chart in Google Sheets

How to Add a Vertical Line to a Chart in Google Sheets

How to Add Average Line to Chart in Google Sheets