List.Accumulate

List

Accumulates a result by applying a function to each item in a list, starting from an initial seed value.

Syntax

List.Accumulate(list as list, seed as any, accumulator as function) as any

Parameters

Name	Type	Required	Description
`list`	`list`	Yes	The list of items to process.
`seed`	`any`	Yes	The initial value to start accumulating from.
`accumulator`	`function`	Yes	A function (state, current) => newState that combines each item with the accumulated state.

Return Value

any — The final accumulated value after processing all items in the list.

Remarks

List.Accumulate is M's "reduce" or "fold" function. It processes each item in a list sequentially, carrying forward a state value that gets updated by the accumulator function. The final state is returned.

This is one of the most powerful list functions — it can implement running totals, string building, multi-step replacements, and any logic that requires carrying state across items.

Examples

Example 1: Sum quantities manually

let
    Quantities = Table.Column(Sales, "Quantity"),
    Total = List.Accumulate(Quantities, 0, (state, current) => state + current)
in
    #table({"TotalQuantity"}, {{Total}})

Result

	TotalQuantity
1	35

Compatibility

✓ Power BI Desktop✓ Power BI Service✓ Excel Desktop✓ Excel Online✓ Dataflows✓ Fabric Notebooks