Master MAKEARRAY: Creating Dynamic Arrays with Custom Logic in Excel 365

This formula creates a 10-row by 10-column array where each cell contains the product of its row and column indices. The LAMBDA function receives the current row (r) and column (c) position and multiplies them together. This generates a complete multiplication table instantly without manual data entry.

This formula generates a 5-row by 4-column invoice structure. Column 1 labels items, column 2 contains base amounts (100, 200, 300...), column 3 shows tax rates (0.1 or 10%), and column 4 calculates tax amounts. The nested IF statements create different calculations per column while MAKEARRAY handles the row iteration.

This formula creates a 12-month amortization preview showing month numbers, remaining balance, and monthly payment amounts. Each row represents a month, with calculations that decrease the balance and show consistent payment amounts. The LAMBDA function applies different formulas based on the column index (c) to show period, balance, and payment.

This combination generates a 20×3 array with row numbers, multiples of 10, and squares, then filters to show only rows where the first column exceeds 5. MAKEARRAY creates the data structure while FILTER applies conditional logic to the results, enabling sophisticated data selection based on calculated criteria.

Generates a 10×2 array with random numbers in the first column and row indices in the second column, then sorts by the first column in descending order. This combination creates randomized datasets that are automatically organized, useful for Monte Carlo simulations or randomized testing scenarios that require structured output.

Creates a 10×3 array where the first column shows row numbers and subsequent columns contain XLOOKUP results based on the row index. This enables dynamic lookup table generation that automatically expands or contracts based on source data changes, eliminating manual table maintenance.

Creating a 1×1 array (single cell)

Behavior: MAKEARRAY(1, 1, LAMBDA(r, c, 42)) returns a single-cell array containing 42. This is valid but rarely useful; typically indicates a formula design issue.

Solution: If you need a single value, use the direct calculation instead of MAKEARRAY. Reserve MAKEARRAY for multi-cell arrays where its benefits justify the added complexity.

Single-cell arrays behave identically to scalar values in most Excel functions, so the distinction rarely matters in practice.

LAMBDA function returns different data types across cells

Behavior: MAKEARRAY can mix text, numbers, dates, and logical values in the same array. Excel coerces types based on context when the array is used in formulas.

Solution: Ensure consistent data types when possible. If mixing types is necessary, be explicit about formatting: =MAKEARRAY(5, 2, LAMBDA(r, c, IF(c=1, TEXT(r, "0"), r*10))).

Mixed-type arrays can cause unexpected behavior in subsequent formulas like SUM() or AVERAGE(). Test thoroughly when intentionally mixing data types.

MAKEARRAY with zero rows or columns

Behavior: =MAKEARRAY(0, 5, LAMBDA(r, c, r*c)) or =MAKEARRAY(5, 0, LAMBDA(r, c, r*c)) returns #VALUE! error. MAKEARRAY requires positive integers for both dimensions.

Solution: Always use positive integers ≥1 for rows and cols. If you need conditional array sizing, use MAX: =MAKEARRAY(MAX(1, A1), MAX(1, B1), LAMBDA(r, c, r*c)) to prevent zero values.

This safeguard prevents accidental empty array generation, but can be overridden with explicit error handling if empty arrays are desired in your logic.