DAX function

DATESINPERIOD — DAX function reference

A rolling window of dates.

Syntax

dax

DATESINPERIOD(<dates>, <start_date>, <number_of_intervals>, <interval>)

dax

CALCULATE(SUM(Sales[Amount]), DATESINPERIOD('Date'[Date], MAX('Date'[Date]), -3, MONTH))

→ Rolling 3-month value

dax

CALCULATE(SUM(Sales[Amount]), DATESINPERIOD('Date'[Date], MAX('Date'[Date]), -12, MONTH))

→ Trailing 12-month sales, anchored to the last date in context

DATESINPERIOD supplies the window of dates and AVERAGEX evaluates the daily total for each before averaging.

dax

AVERAGEX(DATESINPERIOD('Date'[Date], MAX('Date'[Date]), -7, DAY), CALCULATE(SUM(Sales[Amount])))

→ A 7-day moving average of daily sales

The window anchors to start_date and extends backward (negative count) or forward (positive) — using MAX('Date'[Date]) as the anchor is essential so the window follows whatever date is currently selected, not a hardcoded date.
Unlike DATESYTD/SAMEPERIODLASTYEAR, DATESINPERIOD doesn't require the date table to start at a period boundary, making it the right choice for genuinely rolling (not calendar-aligned) windows like trailing-N-days.

From Time intelligence