Roll-up summary filter criteria
Key Takeaway
Filter criteria limit which detail records a roll-up summary field calculates. Their "contains" and "does not contain" operators don't behave the way they do in list views, reports, and dashboards.
A roll-up summary field sits on the master record of a master-detail relationship and calculates a value from its detail records, such as a count or a total. Filter criteria let you include only some of those detail records in the calculation instead of all of them. You can predict what the roll-up will show when you know which fields and operators a filter can use and how they behave.
What filter criteria do
The summary type is what the field calculates: a COUNT of the related detail records, or the SUM, MIN, or MAX of a field on those records.
Filter criteria are optional. You add them when you want only a selected group of detail records in the summary calculation. Without them, the calculation covers all the related detail records.