To calculate a moving or rolling average, you can use a simple formula based on the AVERAGE function with relative references. In the example shown, the formula in E7 is: =AVERAGE(C5:C7) As the formula is copied down, it calculates a 3-day moving average based on the sales value for the current day and the two previous days. Below is a more flexible option based on the OFFSET function which handles variable periods. About moving averages A moving average (also called a rolling average) is an average based on subsets of data at given intervals. Calculating an average at specific intervals smooths out the data by reducing the impact of random fluctuations. This makes it easier to see overall trends, especially in a chart. The larger the interval used to calculate a moving average, the more smoothing that occurs, since more data points are included in each calculated average.