If you open the dropdown menu 
to the right of a field in the Values area in the lower areas section of the field list, you will find the Value Settings option. Alternatively, you will find this option via the context menu by right-clicking directly in the Pivot table report (select a cell below the header title Sum of...).
The value settings dialog box contains the tabs Summarize values and Show values as, which give you various summary functions and calculation options to choose from.
Value settings, "Summarize values" tab
The results in the pivot table report are automatically displayed as a sum if a number field was identified in the Values area. If the field has values other than numbers, the results are calculated as a count.
You can customize the display of the results. The specified selection applies to the subtotals of the higher-level field and also to the subgrouped fields.
To do this, click the dropdown menu to the right of the desired field in the Values area (in the areas section) and select the Value settings option. In the dialog box that then opens, choose the Summarize values tab.
In the upper section of the tab, you will find "Summarize values by" with the following options for displaying the values:
▪Sum: The subtotals are displayed as the sum of the single values.
▪Count: Returns the number of single values that occur. Works the same as the COUNTA function.
▪Average: Returns the average value of the occurring single values.
▪Maximum: Returns the largest occurring single value.
▪Minimum: Returns the smallest occurring single value.
▪Product: Returns the multiplied value of the occurring single values.
▪Count numbers: Returns the count of values that are numbers. Works the same as the COUNT function.
▪Standard deviation (sample): Returns the estimated value for the standard deviation of a population based on a sample. Works the same as the STDEV.S function.
▪Standard deviation (population): Returns the standard deviation of a population. Works the same as the STDEV.P function.
▪Variance (sample): Returns the estimated value for the variance of a population based on a sample. Works the same as the VAR.S function.
▪Variance (population): Returns the variance of a base population. Works the same as the VAR.P function.
Tip: If you only want to change the subtotals to a certain display, you can make the required changes in the Row/Column labels area with the Field settings option, see previous section Field settings (Row/column labels area). If, on the other hand, you want to show or hide the Grand totals for columns/rows, you will find the options available under Pivot table settings.
Furthermore, you will find the Custom name option in the tab. Here you can rename the field so that it appears in the pivot table with a different name. See also section Working with the field list: Areas section.
Value settings, "Show values as" tab
In the Show values as tab you will find various options how to display the results of the pivot table, for example, as percentage values.
Tip: You can also drag the same field several times into the Values area. If you then apply different output settings to the copy of the field using Show values as (e.g. for one field standard values and for the other field percentage values), you can clearly compare the different output values in the pivot report.
In the upper section of the dialog box you will find the section Show values as with choices for calculating the values. Depending on the calculation type, additional entries appear in the Base field and Base item lists below.
▪Standard (no calculation): Displays the value as usual.
▪% of grand total: Each item is displayed as a percentage of the grand total.
▪% of column total: For each column, the total is set as a 100% reference, and each item in the column is shown as a percentage of that total.
▪% of row total: For each row, the total is set as a 100% reference, and each item in the row is shown as a percentage of that total.
▪% of: A column or row field is set as a 100% reference, and all other values are displayed as a percentage of this reference value. The required entries must be selected from the base field list and base item list.
▪% of parent row total: Displays the percentage of an item relative to the higher-level item (= parent) in the row structure.
▪% of parent column total: Displays the percentage of an item relative to the higher-level item (= parent) in the column structure.
▪% of parent total: Displays the percentage of an item relative to any (selectable) higher-level item in the structure. The required entry must be selected from the base field list.
▪Difference from: Displays the absolute difference of the values from the selected reference value. The required entries must be selected from the base field list and base item list.
▪% difference from: Displays the percentage difference of the values from the selected reference value. The required entries must be selected from the base field list and base item list.
▪Running total in: Displays the cumulative absolute values of the successive items. The required entry must be selected from the base field list.
▪% running total in: Displays the cumulative percentage values of the successive items. The required entry must be selected from the base field list.
▪Rank smallest to largest: Displays the rank of selected values in a specific field. The smallest item in the field is ranked 1. The required entry must be selected from the base field list.
▪Rank largest to smallest: As above, but the largest element in the field is ranked 1.
▪Index: Displays the weighting of the values in relation to the grand row total and grand column total. The higher the index value, the greater the weighting of the value on the grand row/column total. For the index value, this formula applies:
| value in cell x grand total of the pivot table grand row total x grand column total |
You can use the Number format button in the tab to permanently adjust the display of the desired number format. For details on the various number formats, see the List of all number formats.
Note: The changes to the number format that you make here are permanently applied. If you change the number format using the cell formatting only, the changes are discarded when the data is refreshed. The number formatting of the source range also is not adopted in the pivot table.