A categorized reference of common DAX functions — aggregation, filter, iterator, time intelligence, and more — linking to full explanations where available.

DAX Function Reference

A quick-scan index of the DAX functions most commonly used in Power BI, grouped by category. Where a function has a full explanation elsewhere on this site — syntax, examples, common mistakes — the name links to it. Functions without a dedicated page get a one-line description here, since they're simple enough not to need one.

Aggregation Functions

Function	Description
`SUM`	Adds up all values in a column.
`AVERAGE`	Returns the arithmetic mean of a column.
`COUNT`	Counts rows where the column contains a number.
`COUNTA`	Counts rows where the column contains any non-blank value.
COUNTROWS	Counts the rows in a table, regardless of column content.
DISTINCTCOUNT	Counts the distinct values in a column.
`MIN` / `MAX`	Returns the smallest or largest value in a column.

These accept a single column and evaluate it within the current filter context — no row-by-row iteration involved. See Measures for how they're typically wrapped into named calculations.

Filter & Context Functions

Function	Description
CALCULATE	Evaluates an expression in a modified filter context — the most-used function in DAX.
FILTER	Returns a table containing only rows that meet a condition.
ALL, ALLEXCEPT, ALLSELECTED & REMOVEFILTERS	Remove or partially restore filters — the basis of percent-of-total and grand-total patterns.
KEEPFILTERS	ANDs a filter with an existing one on the same column instead of CALCULATE's default of replacing it.
CROSSFILTER	Changes a relationship's cross-filter direction or disables it, for a single calculation.
EARLIER	Reaches back to an outer row context from inside a nested one — mostly replaced by `VAR` in modern DAX.

See Filter Context for how these functions interact with what's currently filtering a calculation.

Iterator (X) Functions

Function	Description
SUMX	Evaluates an expression per row, then sums the results.
`AVERAGEX`	Evaluates an expression per row, then averages the results.
`COUNTX` / `COUNTAX`	Evaluates an expression per row, then counts non-blank results.
`MAXX` / `MINX`	Evaluates an expression per row, then returns the largest or smallest result.
RANKX	Ranks a value against every other value produced by an expression across a table.

All of these evaluate their expression once per row of the given table — see Iterators for how row-by-row evaluation actually works, and Performance Optimization for when iterators get expensive.

Time Intelligence Functions

Function	Description
`TOTALYTD` / `TOTALQTD` / `TOTALMTD`	Running total from the start of the year, quarter, or month.
`SAMEPERIODLASTYEAR`	The same date range, shifted back exactly one year.
DATEADD	Shifts a date range by a given number of years, quarters, months, or days — preserving the exact shape of the current selection.
PARALLELPERIOD	Like `DATEADD`, but always snaps the result out to the entire shifted period, regardless of the current selection's shape.
`FIRSTDATE` / `LASTDATE`	The earliest or latest date in the current filter context.
`STARTOFMONTH` / `ENDOFMONTH`	The first or last date of the month containing the current context.
`STARTOFYEAR` / `ENDOFYEAR`	The first or last date of the year containing the current context.

See Time Intelligence for the full explanation, or the DAX Time Intelligence Cheat Sheet for a fast, scannable version of this same table with examples.

Relationship Functions

Function	Description
RELATED	Pulls a single value across a relationship, from the "one" side.
RELATEDTABLE	Pulls every related row across a relationship, from the "one" side, as a table.
LOOKUPVALUE	Retrieves a value from another table by matching columns — works without an existing relationship.
USERELATIONSHIP	Activates a specific inactive relationship for one calculation.

Table Functions

Function	Description
SUMMARIZE	Groups a table by columns, optionally computing an aggregation per group.
ADDCOLUMNS	Adds computed columns to a table, evaluated per row — keeps every original column too.
SELECTCOLUMNS	Returns a table with only specific columns, optionally renamed — drops everything else entirely.
VALUES	Returns the distinct values of a column — adds an extra blank row for unmatched fact rows if a relationship's referential integrity is violated.
DISTINCT	Returns the distinct values of a column, without VALUES' referential-integrity blank row.
TOPN	Returns the top (or bottom) N rows of a table by a given expression.
UNION	Stacks two or more tables into one — matches columns by position, not by name.
EXCEPT / INTERSECT	Returns rows in one table but not another, or rows common to both — same positional column matching as UNION.

Logical Functions

Function	Description
IF	Returns one of two results based on whether a condition is true.
SWITCH	Evaluates an expression against multiple possible values — a flatter alternative to nested `IF`.
`AND` / `OR` / `NOT`	Combine or invert logical conditions. (`&&` and `\|\|` work the same as `AND`/`OR` inline.)
IFERROR	Returns a fallback value if an expression errors — doesn't catch or replace a BLANK() result.
SELECTEDVALUE	Returns a column's value when exactly one value is selected, and a fallback otherwise.

Text Functions

Function	Description
`CONCATENATE`	Joins two text values. (The `&` operator does the same thing, and is more common in practice.)
UPPER / LOWER	Converts text to all uppercase or lowercase.
LEFT / RIGHT / MID	Extracts a substring from the start, end, or middle of a text value — MID counts positions from 1, unlike Power Query's Text.Middle.
TRIM	Removes leading and trailing spaces — and collapses internal double spaces too, unlike Power Query's Text.Trim.
`LEN`	Returns the number of characters in a text value.
`FORMAT`	Converts a number or date to text, using a specified format.

Date & Time Functions

Function	Description
`DATE`	Constructs a date from year, month, and day values.
TODAY / NOW	Returns the current date, or current date and time — frozen at refresh time in a calculated column, live in a measure.
`YEAR` / `MONTH` / `DAY`	Extracts the year, month, or day from a date.
CALENDAR	Generates a continuous table of dates between a start and end date.
CALENDARAUTO	Generates a continuous date table automatically, spanning every date column in the entire model — not just one table.
DATEDIFF	Returns the difference between two dates, in a specified unit — counts calendar boundaries crossed, not full elapsed periods.

See Date Tables for how CALENDAR/CALENDARAUTO fit into building a proper date table.

Information Functions

Function	Description
ISBLANK	Returns true if a value is blank — not the same as testing `= 0`, since BLANK() = 0 is also true.
`ISERROR`	Returns true if an expression would produce an error.
`HASONEVALUE`	Returns true if exactly one value is visible in the current filter context for a column.
DIVIDE	Divides two numbers, returning blank (or a specified fallback) instead of an error on division by zero.

DIVIDE in particular should be the default over the / operator in report-facing measures — see Best Practices for where this comes up.

Beyond Built-In Functions

Every function above is built into DAX. As of the June 2026 release, DAX also supports user-defined functions — package a calculation once with the FUNCTION keyword, and reuse it across measures, calculated columns, and visual calculations like any built-in function. See DAX User-Defined Functions (UDFs) for the syntax and the val/expr distinction that controls how a UDF's parameters get evaluated.

How to Use This Reference

Linked functions have a full page: syntax, worked examples, common mistakes, and best practices.
Unlinked functions are simple enough that a one-line description is genuinely sufficient — Microsoft's own DAX function reference covers full parameter lists for anything not detailed here.
Start with Introduction and Basics if any of this terminology (filter context, row context, iterator) isn't yet familiar — the function list assumes those concepts.

Next Steps

Continue learning DAX:

DAX Function Reference

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