Goal: Calculate sales for "Red" products only.
Watch how CALCULATE changes the "Filter Context" temporarily.
Ready...
💻 DAX Formula
-- Measure 1: Standard Sum
MEASURE Total Sales = SUM( Sales[Amount] )
-- Measure 2: Change Context with CALCULATE
MEASURE Red Sales =
CALCULATE (
[Total Sales], // 1. The Expression
Sales[Color] = "Red" // 2. The New Filter
)