Grouping subtotals and grand totals
Key Takeaway
Group the report rows, then summarize a numeric column. Salesforce shows each summary as a subtotal for every group and as a grand total for all report data.
Grouping sorts report rows into sections based on a field, such as Stage or Priority. When you summarize a numeric column, Salesforce calculates a subtotal for every group and a grand total for all report data. You get these totals without adding numbers by hand or writing a formula.
Where subtotals and grand totals come from
Subtotals come from two pieces working together. The first piece is grouping, which splits the records into sections. You add a group from the "Add group" dropdown. The second piece is a summary on a numeric column, such as Amount, Age, or Probability. The summary tells Salesforce what to calculate for each section.
Each summary you apply appears as a subtotal for every group and as a grand total at the bottom of the report. On the run page, the summaries also appear at the top of the report.
For example, imagine a case report grouped by Priority, with the Age column summarized with Average. Each Priority group shows a subtotal: the average Age of the cases in that group. At the bottom of the report, the grand total shows the average Age of all the cases in the report.