How to calculate the grand total from related list records.
- Navigate to the Object where the related list is located: Setup > Customize > Field Service > [Object_Name] > Fields
- Under [Object] Custom Fields & Relationships, click New.
- Select “Roll-Up Summary” and click Next.
- Field Label name as preferred (i.e. Grand Total) and click Next.
- Summarized Object: Select the related list.
- Select Roll-Up Type: Select the preferred option. (i.e: SUM)
- Field to Aggregate: Select the field to calculate the value.