DATESINPERIOD

DATESINPERIOD is a DAX function used in Power BI, Analysis Services, and Power Pivot to return a table of dates from a date column that fall within a specific period. The period is anchored at StartDate and spans a number of intervals at a chosen granularity such as day, week, month, quarter, or year.

Syntax: DATESINPERIOD (Dates, StartDate, NumberOfIntervals, Interval)

Parameters:

- Dates: a column of date values that defines the valid date domain, typically from a Date table.

- StartDate: a scalar date that serves as the anchor for the period.

- NumberOfIntervals: an integer specifying how many intervals to include. A negative value looks backward from StartDate; a positive value looks forward.

- Interval: the interval granularity; options include DAY, WEEK, MONTH, QUARTER, or YEAR.

Return: a one-column table containing the dates from Dates that lie within the defined period, inclusive where applicable. This table is often used as a filter in measures via CALCULATE or similar expressions.

Usage notes: DATESINPERIOD is a common tool for time-intelligence calculations, enabling calculations such as “last N months” or “next N days” by combining it with a measure. It relies on a properly configured Date table and is frequently paired with other time-based functions like CALCULATE, DATESBETWEEN, or DATEADD to build robust period analyses.

Examples:

- Last 12 months ending at the latest date: CALCULATE(SUM(Sales[Amount]), DATESINPERIOD('Date'[Date], MAX('Date'[Date]), -12, MONTH))

- Next 30 days from today: DATESINPERIOD('Date'[Date], TODAY(), 30, DAY)