Pivot tables have a built-in feature to calculate running totals.

Fields

The source data contains three fields:Date,Sales, andColor.

Only two fields are used to create the pivot table:DateandSales.

Field list for running total pivot table

Then add the Month field to the pivot table directly.

Steps to make this pivot table

Field list for running total pivot table

Field list for running total pivot table

Field list for running total pivot table

Field list for running total pivot table

Date grouping for running total pivot table

Total field settings

Running total field settings