Database Rollup aggregation constraints for multi-property calculations

Answer

Notion’s Rollup property can reference only a single property from the related database, so you cannot aggregate two or more numeric fields directly in one Rollup.

Confirmed facts

• The Rollup UI picker allows selection of exactly one source property.
• All aggregation functions (Sum, Average, Median, Min, Max, Count, etc.) operate on that single chosen property.
• This behavior is consistent across web, desktop, and mobile clients in the current stable release.
• No hidden setting or advanced option enables multi‑property selection.

Likely explanation

The design treats a Rollup as a simple aggregation of one column from the related table; extending it to multiple columns would require a more complex UI and execution model, which Notion has not implemented.

Steps to achieve multi‑property aggregation

1. Create a Relation property linking the source database to the target database.
2. Add two (or more) numeric properties in the related database that you want to combine (e.g., Cost A and Cost B).
3. Add a Rollup property for each numeric field, pointing to the Relation and selecting the respective property; choose the desired aggregation (Sum, Average, etc.).
4. Add a Formula property that references the two Rollup results and performs the combined calculation (e.g., prop("Rollup A") + prop("Rollup B") or a weighted average).
5. Verify the Formula returns the expected value for a few sample records.