The Only DAX Functions Cheat Sheet You'll Ever Need (Power BI 2026)

You open Power BI. You need to write a measure. You half-remember the syntax. You Google it. Again.

Sound familiar?

Every Power BI user — from beginners to mid-level analysts — wastes hours every week searching for DAX syntax they've already used before. The problem isn't intelligence. It's the lack of one trusted, well-organized DAX reference that actually explains when and why to use each function — not just the syntax.

This is that reference.

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Why This Matters

DAX (Data Analysis Expressions) is the engine behind every Power BI report that actually does something useful. It's what separates a static table from a dynamic business intelligence system.

But DAX has over 200+ functions — and most tutorials dump a raw list on you without context. The result? Analysts who memorize syntax but don't understand logic. Interviews failed because someone couldn't explain why CALCULATE works the way it does. Reports that technically run but produce the wrong numbers.

This cheat sheet is organized by purpose — the way a working analyst thinks — not alphabetically.

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Core Content: DAX Functions by Category

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A. Aggregation Functions

Used to summarize data across rows

Pro Note: COUNTROWS on a filtered table is often more reliable than COUNT on a column — especially after FILTER() or CALCULATETABLE().

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B. Filter Context Functions

The heart of DAX — controls what data your measure sees

Critical Concept: CALCULATE doesn't just filter — it transforms the filter context. Every argument after the first is a filter modifier. This is the most important DAX function to master.

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C. Time Intelligence Functions

Only work with a properly marked Date Table

Interview Trap: Time intelligence functions return tables of dates, not values. They must always be wrapped inside CALCULATE.

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D. Iterator (X) Functions

Row-by-row calculation — then aggregate

When to use X functions: When your calculation needs per-row logic before aggregation. Classic example: Revenue = SUMX(Sales, Sales[Qty] * Sales[Price]) — because multiplying first, then summing, gives the right answer. SUM(Qty) * SUM(Price) does not.

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E. Logical Functions

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F. Text Functions

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G. Relationship & Lookup Functions

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H. Table Functions (Advanced)

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Technical Insight: The 3 DAX Patterns You'll Use 80% of the Time

Pattern 1 — % of Total

% of Total Sales = 
DIVIDE(
    [Total Sales],
    CALCULATE([Total Sales], ALL(Sales)),
    0
)

Pattern 2 — Year-over-Year Growth

YoY Growth % = 
VAR CurrentYearSales = [Total Sales]
VAR PriorYearSales = CALCULATE([Total Sales], SAMEPERIODLASTYEAR('Date'[Date]))
RETURN
DIVIDE(CurrentYearSales - PriorYearSales, PriorYearSales, 0)

Pattern 3 — Running Total

Running Total = 
CALCULATE(
    [Total Sales],
    FILTER(
        ALL('Date'[Date]),
        'Date'[Date] <= MAX('Date'[Date])
    )
)

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Common Mistakes

Mistake 1 — Using SUM when you need SUMX
If your measure involves per-row multiplication or division before aggregation, always use SUMX. SUM aggregates the column as-is.

Mistake 2 — Forgetting to mark the Date Table
Time intelligence functions will return errors or wrong results if your date table isn't marked. Go to Table tools → Mark as date table.

Mistake 3 — Writing nested IFs instead of SWITCH
Deep nested IF statements are unreadable and slower. SWITCH(TRUE(), ...) is the professional pattern.

Mistake 4 — Using FILTER inside CALCULATE on large tables
CALCULATE([Sales], FILTER(Sales, Sales[Region] = "North")) scans the entire table. Use CALCULATE([Sales], Sales[Region] = "North") instead — it uses the column filter directly.

Mistake 5 — Ignoring VAR for performance
Variables aren't just for readability. They're evaluated once and cached. Using [Total Sales] three times in one measure recalculates it three times. VAR x = [Total Sales] calculates it once.

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Pro Tips

• Always use DIVIDE(numerator, denominator, 0) instead of / — it handles division by zero gracefully without breaking your report.
• SELECTEDVALUE(Column, Default) is the clean way to get a single slicer selection. Better than writing IF(HASONEVALUE(...)) every time.
• Format your DAX. Use the DAX Formatter or Power BI Desktop's built-in formatter. Unformatted DAX is a professional red flag.
• Name measures with context: Total Revenue > Revenue. Revenue LY > Last Year Rev. Your future self — and every teammate — will thank you.
• Test measures in a Matrix visual with the relevant dimension on rows. It's the fastest way to validate context behavior.

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Summary

DAX mastery isn't about memorizing 200 functions. It's about deeply understanding:

1. Filter context — what data your measure sees
2. Iterator logic — when to go row-by-row
3. Time intelligence — how to shift periods correctly
4. The 3 core patterns — % of total, YoY, running totals

This cheat sheet covers the 80% of DAX you'll use in 95% of real projects. Save it. Bookmark it. Use it as your reference on every build.

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CTA

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