In time series analysis, a **3-month moving average **is simply the average value of the 3 months leading up to and including a certain month.

The following example shows how to calculate a 3-month moving average for a dataset in Excel.

**Example: Calculate 3-Month Moving Average in Excel**

Suppose we have the following dataset that shows the total sales made during 12 consecutive months by some company:

To calculate the 3-month moving average of the sales values, we can type the following formula into cell **C4**:

**=AVERAGE(B2:B4)
**

We can then click and drag this formula down to each remaining cell in column C:

The values in column C represent the 3-month moving average of the values in the sales column.

For example, the 3-month moving average of sales in March is **25.667**.

We can confirm this is correct by manually calculating the average of sales for the three months leading up to and including this month:

3-Month Moving Avg. of Sales in March: (22+25+30) / 3 = **25.667**

This matches the value calculated by our formula.

Since we clicked and dragged this formula down to each cell in column C, the formula automatically updated to use the most recent 3 months to calculate each 3-month moving average.

For example, cell **C13 **uses the range **C11:C13** to calculate its 3-month moving average:

**Note**: We had to type our formula starting in cell **C4** because this represented the first date that had 3 months to use for calculating the 3-month moving average.

**Additional Resources**

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

How to Calculate a Weighted Moving Average in Excel

How to Calculate a Cumulative Average in Excel

How to Calculate an Exponential Moving Average in Excel