The RELATED() Function: Fetching Values Across Relationships

Overview

The RELATED function retrieves a value from another table along an active many-to-one relationship. It can only be used in a row context—typically inside calculated columns or iterator functions like SUMX—not in simple measures that lack row context.

Think of it as a lookup: for each row in the current table, RELATED follows the relationship to fetch a single matching value from the related table on the "one" side.

Syntax

DAX Syntax

RELATED(<column>)

<column>: A column from the related table on the "one" side of an active many-to-one relationship.
Must be called in row context (calculated column, SUMX, FILTER, etc.).

Example & Dataset

A star schema with a Sales fact table (many rows per product) linked to a Products dimension (one row per product):

Products (Dimension)

ProductID	ProductName	CostPerUnit
P01	Laptop	600
P02	Mouse	8

Sales (Fact)

SaleID	ProductID	Revenue
S01	P01	900
S02	P01	850
S03	P02	25
S04	P02	30

The DAX Code

To compute total profit margin across all sales lines, use SUMX with RELATED to pull each product's cost per unit into the row context of Sales:

Total Profit Margin Measure

Total Profit Margin =
SUMX(
    Sales,
    Sales[Revenue] - ( RELATED(Products[CostPerUnit]) * 1 )
)

Expected Output Visual

A Card visual showing [Total Profit Margin] displays:

Output

SaleID	Revenue	Cost (via RELATED)	Line Profit	Running Total
S01	900	600	300
S02	850	600	250
S03	25	8	17
S04	30	8	22
Total Profit Margin				589

Why Did This Output Happen?

SUMX creates row context on Sales. For each sale row, RELATED(Products[CostPerUnit]) follows the ProductID relationship and returns the matching cost from Products. Line profit is Revenue minus CostPerUnit (quantity assumed 1 per row). Summing 300 + 250 + 17 + 22 = 589 gives total profit margin across all transactions.