Lesson 61 How to Use FILTER in DAX: A Beginner’s Guide

Lesson 61 How to Use FILTER in DAX: A Beginner’s Guide

Welcome back to Virvijay.com, where we simplify Power BI for you! 🎯

In the previous blog, we learned about SUM vs SUMX in DAX. Now, let’s dive into another powerful DAX function: FILTER.

By the end of this blog, you’ll learn:

  • ✅ What is FILTER in DAX?
  • ✅ How FILTER works with other functions like SUMX
  • ✅ Real-world examples for better Power BI analysis
  • ✅ Best practices to optimize FILTER for performance

1️⃣ What is FILTER in DAX?

The FILTER function in DAX returns a table that meets specific conditions. It doesn’t calculate values directly but helps filter data dynamically.

📌 Syntax:

DAX

FILTER(<Table>, <Condition>)

🔍 Think of FILTER as a way to extract specific rows from a table before performing calculations.

2️⃣ How FILTER Works with Other DAX Functions

Since FILTER returns a table, it is often used inside other functions like SUMX, AVERAGEX, COUNTX, etc.

📌 Example: Suppose we have a Sales table, and we want to calculate the Total Sales for Orders above ₹50,000.

👉 Using SUMX with FILTER:

DAX

Total Sales Over 50K = SUMX(FILTER(Sales, Sales[Sales Amount] > 50000), Sales[Sales Amount])

✅ What’s happening?

FILTER(Sales, Sales[Sales Amount] > 50000) extracts only sales above ₹50,000.

SUMX then sums only the filtered values.

🚀 Result: Instead of summing all sales, we only sum sales greater than ₹50,000.

3️⃣ Real-Life Examples of FILTER in DAX

Example 1: Calculate Total Sales for a Specific Region

📌 Suppose we have a column Region in our Sales table. We want to calculate total sales only for the "North" region.

👉 DAX Formula:

DAX

Total Sales North = SUMX(FILTER(Sales, Sales[Region] = "North"), Sales[Sales Amount])

🔍 How it works:

  • FILTER(Sales, Sales[Region] = "North") → Extracts only "North" region sales
  • SUMX → Sums the sales amount of filtered data

Example 2: Count Customers with Sales Above ₹1,00,000

📌 Suppose we want to count how many customers made sales of more than ₹1,00,000.

👉 DAX Formula:

DAX

Customers Over 1L = COUNTROWS(FILTER(Sales, Sales[Sales Amount] > 100000))

🔍 How it works:

  • FILTER(Sales, Sales[Sales Amount] > 100000) → Filters sales above ₹1,00,000
  • COUNTROWS → Counts the number of filtered rows (customers)

Example 3: Average Sales per Customer for a Specific Product

📌 Suppose we have a column Product Name and want to find the average sales per customer for "Laptop" sales.

👉 DAX Formula:

DAX

Avg Sales Laptop = AVERAGEX(FILTER(Sales, Sales[Product Name] = "Laptop"), Sales[Sales Amount])

🔍 How it works:

  • FILTER(Sales, Sales[Product Name] = "Laptop") → Filters only Laptop sales
  • AVERAGEX → Finds the average of the filtered sales
4. Best Practices for Using FILTER in DAX

🚀 To use FILTER efficiently, follow these best practices:

  • Use FILTER only when necessary. If a simple SUM or SUMX works, avoid unnecessary filters.
  • Combine FILTER with CALCULATE for advanced calculations.
  • ✅ Avoid FILTER on large datasets unless optimized properly.
  • ✅ Use Variables (VAR) inside FILTER expressions to improve performance.

📌 Example using CALCULATE + FILTER:

DAX

Total High-Value Sales = CALCULATE(SUM(Sales[Sales Amount]), FILTER(Sales, Sales[Sales Amount] > 100000))

🎯 Why use CALCULATE?

CALCULATE modifies the context and makes FILTER more powerful in complex calculations.

5️⃣ Conclusion: When to Use FILTER in Power BI?

  • 🚀 Use FILTER when you need to extract specific rows before calculation.
  • 🚀 Use FILTER inside SUMX, AVERAGEX, COUNTX for dynamic filtering.
  • 🚀 Use CALCULATE + FILTER for advanced DAX calculations.

By mastering FILTER, you’ll improve your Power BI analysis, dashboards, and performance! 🎯

6️⃣ What’s Next?

📌 In the next blog, you’ll learn:

  • ✅ CALCULATE in DAX: The Most Powerful Function in Power BI
  • ✅ How CALCULATE Works with FILTER
  • ✅ Real-life use cases for Business Analysis

🔔 Stay tuned to Virvijay.com for more Power BI tutorials!

📩 For any queries, reach out to support@virvijay.com

💬 Got questions? Drop them in the comments!

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