How to Change a PivotTable's Calculation in Excel
Besides adjusting the layout of your PivotTable data, you can also change how a PivotTable summarizes values. For example, you might want a PivotTable to display averages instead of totals.
The Value Field Settings dialog box appears. From here, you can select calculation options including Sum, Count, Average, or Max, among others.
When a field containing numeric values is added to a PivotTable, Excel automatically calculates the sum.
The summarized data in the PivotTable changes to use the new calculation.