TL;DR: When a subitem's Numbers column changes, automatically aggregate it (sum, average, min, max, count) into the parent's Numbers column. Parent-level metrics stay accurate without manual updates — feed them straight into dashboards, formulas, or other automations.
What this does
Recipe:"When subitem's numbers column changes, aggregate it by operator into its parent item numbers column."
You pick a Numbers column on the subitem (the source), an aggregation operator (sum, average, min, max, count), and a Numbers column on the parent (the destination). Whenever any subitem's source value changes, the parent's destination value recalculates across all subitems.
Example: subitems have a "Hours logged" Numbers column. The parent has a "Total hours" Numbers column with operator = sum. Every time any subitem's hours change, the parent's total recalculates instantly.
When to use it
Project-level metrics that aggregate from subitem-level inputs (total hours, total cost, item count)
Dashboards driven by parent-level Numbers columns that need to stay live
Feeding aggregated values into other automations (e.g. "when total hours > 100, notify owner")
Formula columns on the parent that depend on a real number, not a calculated mirror
Available operators
Sum — total of all subitem values (most common — totals, costs, hours)
Average — mean of all values (e.g. average task duration)
Min — smallest value (e.g. shortest estimate)
Max — largest value (e.g. highest priority score)
Count — number of subitems with a value (regardless of the value itself)
Before you start
A Numbers column on the subitem (the source)
A Numbers column on the parent item (the destination)
A clear decision on which aggregation operator fits your use case
Set it up
Open Automate → Create on your board.
Copy the recipe text above and find it in your board's automation center, then click Use Template.
Configure:
Subitem numbers column — the source values
Operator — sum, average, min, max, or count
Parent numbers column — where the aggregated value lands
Click Create automation.
Test that it works
Set Numbers values on a few subitems (e.g. 5, 10, 15).
Open the parent. Confirm the destination column shows the correct aggregation (sum = 30, average = 10, count = 3, etc.).
Change one subitem's value. Confirm the parent recalculates.
Add a new subitem with a value. Confirm the parent updates.
Common gotchas
Numbers columns only. Source and destination must both be Numbers type — not Text, not Formula, not Mirror.
Empty subitems are ignored. Subitems with no value in the source column don't contribute to the aggregation.
The destination is a derived value. Don't set the parent's Numbers column manually — it'll be overwritten on the next subitem change.
One operator per automation. If you want both sum AND average on the parent, set up two automations into two different parent columns.