Daily DAX : Day 376 TRUNC

Power BI DAX: TRUNC Function

Overview

The TRUNC function in DAX (Data Analysis Expressions) truncates a number to an integer by removing the decimal part. It does not round the number — it simply chops off the fractional portion.

Syntax

TRUNC(number, [digits])
  • number (Required): The numeric value you want to truncate.
  • digits (Optional): Number of decimal places to keep. Default is 0.

Example:

TRUNC(12.789) → 12

TRUNC(-8.95) → -8 (truncates toward zero)

TRUNC(45.678, 2) → 45.67

Key Behavior

  • Truncates toward zero: Positive and negative numbers are cut off at the decimal point.
  • Not the same as rounding: Use ROUND if you need rounding.
  • Useful for grouping or extracting integer parts without rounding bias.

Use Cases

Use Case Description Example
Extract Integer Part Get whole number from a decimal value. Integer Sales = TRUNC([Total Sales])
Bucket Values Group data into integer-based buckets (e.g., age groups, price tiers). Price Tier = TRUNC([Price], 0) * 10
Avoid Rounding Bias Prevent rounding from skewing averages or totals. Truncated Score = TRUNC([Score], 1)
Time Calculations Strip fractional days from datetime differences. Whole Days = TRUNC([End Date] - [Start Date])

TRUNC vs INT vs FLOOR

Function 12.7 -12.7 Behavior
TRUNC(x) 12 -12 Truncates toward zero
INT(x) 12 -13 Truncates toward negative infinity
FLOOR(x, 1) 12 -13 Rounds down to nearest multiple

Practical Example

Scenario: You have sales data with decimal values, and you want to analyze only the whole dollar amounts.

Whole Dollar Sales = TRUNC([Total Sales])

This removes cents, ensuring no rounding affects your grouping or aggregation.

Use TRUNC when you need clean integer extraction without rounding.

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