
The automatic grouping is a default setting that can be changed. Press the Ungroup button on the Analyze tab of the ribbon.Select a cell inside the pivot table in one of the date fields.If you are using Excel 2016 (Office 365) then the date field is automatically grouped when you add it to the pivot table. You can also create a Calendar Table with the groupings if you are using Power Pivot. Using your own fields from the source data for the different date groups will give you control over the number formatting of the field in the pivot table. I explain this in detail in my article on Grouping Dates in a Pivot Table VERSUS Grouping Dates in the Source Data. The first solution is to create fields (columns) in the source data range with the various groups for Year, Quarter, Month, Days, etc. Since these are text items that represent the days of the year, we won't be able to change the number formatting of the cells directly in Excel. zip, and navigate to the PivotCache folder.

To see that you can change the file extension of the Excel file to. We can actually see this list of text items in the pivotCacheDefinition.xml file. It keeps the month name in the Day field names, and this is actually a grouping of day numbers (1-31) for each month.

When we group the fields, the group feature creates a Days item for each day of a single year. The number formatting does not work because the pivot item is actually text, NOT a date. Nothing changes when we go to Field Settings > Number Format, and change the number format to a custom or date format. If we try to change the number format of the Day/Date field it does not work. It has the following format “Day-Month” or “d-mmm”. When we group a Date field in a pivot table using the Group feature, the number formatting for the Day field is fixed. Skill level: Intermediate Changing the Days Field Number Formatting Doesn't Work Bottom line: Learn how to change the date formatting for a grouped field in a pivot table.
