TOPN()

TOPN() returns a table containing the top (or bottom) N rows, ranked by a given expression — the DAX equivalent of "show me the top 10."

TOPN(
    N Value,
    Table,
    OrderBy Expression,
    [Order]
)

Basic Example

Top 5 Products =
TOPN(
    5,
    ALL(DimProduct),
    [Total Sales]
)

All Products (ranked by Total Sales, descending)
   |
   +-- Tire A     50,000
   +-- Tire B     42,000
   +-- Helmet A   18,000
   +-- Lock A     12,000
   +-- Pump A      9,500
   |
Top 5 Products = these 5 rows

Because TOPN() returns a table, it's typically wrapped in CALCULATE() to restrict a measure to just those top rows, or used inside another table function.

TOPN Inside CALCULATE

Top 5 Sales =
CALCULATE(
    [Total Sales],
    TOPN(
        5,
        ALL(DimProduct),
        [Total Sales]
    )
)

This restricts [Total Sales] to only the 5 highest-selling products, regardless of how many products actually exist in the model.

Order: Descending vs. Ascending

Bottom 5 Products =
TOPN(
    5,
    ALL(DimProduct),
    [Total Sales],
    ASC
)

DESC (default): highest values first -> "top" N
ASC:            lowest values first  -> "bottom" N

TOPN vs. RANKX + FILTER

The same "top N" result can be built by ranking every row and filtering down to the top ranks — TOPN() is the more direct route to the same answer.

Top 5 (via RANKX + FILTER) =
CALCULATE(
    [Total Sales],
    FILTER(
        ALL(DimProduct),
        RANKX(ALL(DimProduct), [Total Sales]) <= 5
    )
)

Top 5 (via TOPN) =
CALCULATE(
    [Total Sales],
    TOPN(5, ALL(DimProduct), [Total Sales])
)

Both return the same result for a clean top-N cutoff. RANKX() combined with FILTER() is worth reaching for instead when the actual rank number needs to be displayed, or when ties need explicit Skip/Dense handling — see RANKX.

Handling Ties at the Cutoff

TOPN() can return more than N rows when there's a tie at the boundary — by default, all tied rows at the cutoff point are included rather than arbitrarily cutting one out.

Requesting Top 3, with a tie at 3rd place:
Tire A   50,000
Tire B   42,000
Helmet A 18,000
Lock A   18,000   <- tied with Helmet A, both included

This is usually the desired behavior for a "top N" report, but it means the result set isn't guaranteed to be exactly N rows.

Common Mistakes

Expecting Exactly N Rows

A tie at the cutoff can return more than N rows — code and visuals consuming the result shouldn't assume an exact row count.

Using TOPN Without CALCULATE for a Scalar Result

TOPN() returns a table. Wrap it in CALCULATE() (or another table-consuming function) rather than expecting it to produce a single value directly.

Choosing TOPN When the Rank Value Itself Is Needed

If a visual needs to display "Rank 1, 2, 3..." next to each row, RANKX() is the right tool — TOPN() only filters to the top rows, it doesn't expose a rank number.

Best Practices

• Wrap TOPN() in CALCULATE() when the goal is a single aggregated result over the top rows.
• Use RANKX() instead when the rank number itself needs to be shown, or when specific tie-handling is required.
• Confirm the table argument (typically wrapped in ALL()) matches the intended comparison scope, the same consideration that applies to RANKX().

Next Steps

Continue learning DAX functions and patterns:

• RANKX
• Ranking Patterns
• FILTER