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This article explains how to use the Excel MAKEARRAY function to build powerful custom generators for dynamic arrays, covering syntax, patterns, optimization strategies, and practical business use cases that advanced users can apply immediately.
1. What is the Excel MAKEARRAY function.
The MAKEARRAY function in Excel is a dynamic array function that creates a new array by running a custom LAMBDA calculation for every cell in a specified row and column dimension.
Instead of typing a formula for each cell, you define the structure once, and MAKEARRAY automatically spills the generated array across the worksheet based on the dimensions you specify.
This enables you to create complex, reusable “array generators” that are often cleaner and faster than manually building nested formulas or copying formulas down and across.
1.1. Basic concept.
At its core, MAKEARRAY answers the question: “If I know how each cell should be calculated from its row and column position, can Excel fill an entire table for me automatically.”
By combining MAKEARRAY with LAMBDA, you can construct custom logic that uses the row number, column number, and any external inputs to produce numbers, text, or logical values that spill into a dynamic array.
This approach is especially useful in advanced Excel models, dashboards, and dynamic reports where the layout must adapt to changing dimensions.
2. Excel MAKEARRAY syntax and arguments.
The official syntax of MAKEARRAY is straightforward but requires an understanding of LAMBDA.
=MAKEARRAY(rows, columns, lambda) | Argument | Required | Description |
|---|---|---|
| rows | Yes | Number of rows in the generated array. |
| columns | Yes | Number of columns in the generated array. |
| lambda | Yes | A LAMBDA function that receives two parameters: row index and column index, and returns the value for that cell. |
The LAMBDA inside MAKEARRAY always receives the row and column indices in this order.
=MAKEARRAY( rows, columns, LAMBDA(row, col, <expression using row and col>) ) The expression can be a simple arithmetic calculation or a complex combination of functions, including other dynamic array formulas.
Note : MAKEARRAY is available only in Excel versions that support dynamic array formulas and the LAMBDA function, such as Microsoft 365 and Excel for the web.
3. First steps: simple MAKEARRAY examples.
Before building advanced custom generators, it is useful to understand a few basic patterns for the Excel MAKEARRAY function.
3.1. Generating a simple sequence table.
The following example generates a 5x5 table where each cell contains its row number.
=MAKEARRAY( 5, 5, LAMBDA(r, c, r) ) This formula spills a 5 by 5 array in which every column repeats 1 to 5 downward.
The next variation uses both row and column indices to create a multiplication table.
=MAKEARRAY( 10, 10, LAMBDA(r, c, r * c) ) This is equivalent to filling a 10x10 multiplication table but is defined only once as a single dynamic array formula.
3.2. Generating text patterns.
MAKEARRAY is not limited to numbers.
The following formula generates labels such as “R1C1”, “R1C2”, and so on, which can be used for debugging or teaching purposes.
=MAKEARRAY( 4, 4, LAMBDA(r, c, "R" & r & "C" & c) ) This demonstrates that your custom generator can return text strings for each position.
4. Custom generators with external ranges.
The true strength of MAKEARRAY custom generators appears when you reference external ranges and parameters inside the LAMBDA.
This enables dynamic array formulas that respond to changes in input tables or criteria ranges without reauthoring the MAKEARRAY logic.
4.1. Mapping row and column indices to a data range.
Assume you have a data range named Sales with 12 rows and 4 columns.
You can reconstruct or transform that range using MAKEARRAY as follows.
=MAKEARRAY( ROWS(Sales), COLUMNS(Sales), LAMBDA(r, c, INDEX(Sales, r, c)) ) This formula simply reproduces the Sales range, but you can modify the returned value to apply transformations.
=MAKEARRAY( ROWS(Sales), COLUMNS(Sales), LAMBDA(r, c, INDEX(Sales, r, c) * 1.1) ) This version multiplies all values by 1.1, which could represent a 10 percent scenario increase.
4.2. Conditional transformation with IF logic.
You can implement row and column specific rules using conditional logic.
The following example applies a different factor by column, using a helper range named Factors with one row and the same number of columns as Sales.
=MAKEARRAY( ROWS(Sales), COLUMNS(Sales), LAMBDA(r, c, LET( value, INDEX(Sales, r, c), factor, INDEX(Factors, 1, c), IF(value = "", "", value * factor ) ) ) ) This structure resembles map operations in functional programming, where MAKEARRAY iterates each element and LAMBDA applies a transformation.
By using LET inside the LAMBDA, you control complexity and optimize calculation performance.
5. Designing advanced custom generators in Excel.
Advanced use of the Excel MAKEARRAY function focuses on designing reusable generator patterns.
These patterns can be adapted to various business models without rewriting the entire logic.
5.1. Calendar grid generator.
Suppose you want to generate a monthly calendar grid that starts on Monday and fills dates according to a given month in cell B1.
Assume B1 contains the first day of the month, for example 2025-01-01.
=MAKEARRAY( 6, 7, LAMBDA(r, c, LET( firstDay, EOMONTH($B$1, -1) + 1, startOffset, WEEKDAY(firstDay, 2) - 1, dayNum, (r - 1) * 7 + c - startOffset, IF(OR(dayNum < 1, dayNum > DAY(EOMONTH($B$1, 0))), "", DATE(YEAR($B$1), MONTH($B$1), dayNum) ) ) ) ) This formula produces a dynamic array representing the calendar grid for the month in B1.
If you change the month in B1, the entire calendar recalculates automatically.
Because the generator is defined via MAKEARRAY, the structure is clear and located in a single formula rather than many scattered references.
5.2. Custom generator for grading bands.
Consider a situation where you want to convert numeric scores to letter grades across a two dimensional table.
Let the numeric scores be stored in a range named Scores.
You can build a MAKEARRAY generator that returns letter grades based on score ranges.
=MAKEARRAY( ROWS(Scores), COLUMNS(Scores), LAMBDA(r, c, LET( s, INDEX(Scores, r, c), IF(s = "", "", IF(s >= 90, "A", IF(s >= 80, "B", IF(s >= 70, "C", IF(s >= 60, "D", "F")))) ) ) ) ) This type of custom array generator removes the need for separate helper formulas and can be reused wherever a grade classification is required.
It also scales naturally when the Scores range grows.
5.3. Randomized data generator for simulations.
In modeling scenarios, you often require random samples or trial data sets.
MAKEARRAY can generate such structures with a single formula.
=MAKEARRAY( 1000, 3, LAMBDA(r, c, CHOOSE( c, NORMINV(RAND(), 100, 15), RAND(), RANDBETWEEN(1, 10) ) ) ) Here column 1 is drawn from a normal distribution using NORMINV, column 2 is a uniform random value between 0 and 1, and column 3 is a random integer between 1 and 10.
This dynamic array can serve as an input table for Monte Carlo simulations or sensitivity analyses.
Note : When using MAKEARRAY with volatile functions such as RAND or RANDBETWEEN, recalculation may trigger frequently and impact performance in large workbooks.
6. Combining MAKEARRAY with other dynamic array functions.
Dynamic array formulas in Excel are most powerful when you combine functions rather than use each in isolation.
MAKEARRAY plays well with BYROW, BYCOL, MAP, REDUCE, and SCAN, enabling very concise yet expressive models.
6.1. MAKEARRAY and BYROW or BYCOL.
MAKEARRAY can generate raw data, while BYROW or BYCOL can aggregate or summarize it.
Consider a generator that creates a 100x10 matrix of random values.
=MAKEARRAY( 100, 10, LAMBDA(r, c, RAND()) ) You can obtain the average of each column via BYCOL.
=BYCOL( MAKEARRAY(100, 10, LAMBDA(r, c, RAND())), LAMBDA(col, AVERAGE(col)) ) This pattern illustrates a clear separation between data generation (MAKEARRAY) and aggregation (BYROW or BYCOL).
6.2. MAKEARRAY and MAP.
MAP iterates over existing arrays, while MAKEARRAY creates arrays from scratch.
You can design a workflow where MAKEARRAY generates an array and MAP applies further processing.
=MAP( MAKEARRAY(10, 5, LAMBDA(r, c, r * c)), LAMBDA(x, x ^ 2) ) This formula first creates a 10 by 5 multiplication table and then squares every element.
Using MAKEARRAY and MAP together keeps formulas readable and easier to maintain than deeply nested expressions.
7. Performance and optimization strategies.
Advanced users rely on the Excel MAKEARRAY function heavily, so performance considerations are important.
Dynamic arrays can produce thousands of cells with a single formula, which can become expensive if each cell performs complex operations.
7.1. Use LET to avoid repeated calculations.
LET allows you to define reusable names inside a formula, reducing redundant calculations and improving performance.
When your custom generator uses the same calculation multiple times, store it in a LET variable.
=MAKEARRAY( ROWS(Data), COLUMNS(Data), LAMBDA(r, c, LET( value, INDEX(Data, r, c), adj, value * GlobalFactor, result, adj + LocalOffset, result ) ) ) This avoids recalculating INDEX(Data, r, c) multiple times inside the LAMBDA and makes the structure easier to read.
7.2. Limit array dimensions to what you actually need.
Overallocating rows or columns in MAKEARRAY wastes resources and may slow down recalculation.
Whenever possible, parameterize the dimensions using ranges or named formulas that reflect the real size of your data.
=MAKEARRAY( COUNTA(CustomerList), 3, LAMBDA(r, c, <logic>) ) By tying the array size to the count of a list, the generator automatically adapts to changes without manually editing the formula.
7.3. Avoid volatile functions when not necessary.
Volatile functions such as NOW, TODAY, OFFSET, INDIRECT, and RAND recalculate more frequently.
If these functions are used inside MAKEARRAY, the entire array recalculates regularly, which may cause noticeable delays in large models.
Prefer static or parameter driven designs, or restrict volatile usage to smaller helper arrays.
Note : When performance becomes an issue, consider splitting one large MAKEARRAY generator into multiple smaller arrays to control recalculation scope.
8. Practical business use cases for MAKEARRAY custom generators.
The theoretical patterns described above become most valuable when translated into concrete business scenarios.
The following examples illustrate how advanced users employ MAKEARRAY in real workbooks.
8.1. Dynamic pricing matrix.
Assume you manage a pricing model where rows represent products and columns represent quantity tiers.
You want a table that shows calculated prices for any combination based on base price, discount rules, and quantity breaks.
| Input | Description |
|---|---|
| Products | List of product IDs and base prices. |
| Quantities | List of break quantities for columns. |
| Rules | Business logic defining discounts by quantity. |
A custom generator may look like the following.
=MAKEARRAY( ROWS(Products), ROWS(Quantities), LAMBDA(r, c, LET( basePrice, INDEX(Products[BasePrice], r), qty, INDEX(Quantities[Qty], c), discount, GETPIVOTDATA("Discount", RulesPivot, "Qty", qty), basePrice * qty * (1 - discount) ) ) ) This structure yields a dynamic pricing matrix that updates automatically when product lists, quantity tiers, or discount rules change.
8.2. KPI heatmap generator.
For dashboards, it is common to build KPI matrices where rows are business units and columns are time periods.
MAKEARRAY can generate normalized KPI values that are then visualized using conditional formatting.
=MAKEARRAY( ROWS(Units), COLUMNS(Periods), LAMBDA(r, c, LET( actual, INDEX(Actuals, r, c), target, INDEX(Targets, r, c), IF(target = 0, 0, (actual - target) / target) ) ) ) This formula returns performance deviations as percentages, suitable for coloring in a heatmap layout.
All logic is contained in one generator, which simplifies maintenance compared to individual cell formulas.
8.3. Scenario comparison tables.
MAKEARRAY can produce side by side comparison tables for multiple scenarios without physically duplicating raw data.
For example, let there be three scenarios represented by multipliers stored in a horizontal range named ScenarioFactor.
=MAKEARRAY( ROWS(BaseValues), COLUMNS(ScenarioFactor), LAMBDA(r, c, INDEX(BaseValues, r, 1) * INDEX(ScenarioFactor, 1, c) ) ) This yields a table where each column corresponds to a scenario and each row to a base line item.
You can feed this generator into charts or further dynamic array formulas to build interactive analysis tools.
9. Common pitfalls and debugging techniques.
Even for experts, dynamic array formulas with MAKEARRAY and LAMBDA can be challenging to debug.
Understanding typical pitfalls allows you to correct errors quickly.
9.1. Mismatch between declared dimensions and underlying ranges.
A frequent issue is declaring more rows or columns in MAKEARRAY than exist in the referenced ranges, which can lead to #REF errors or empty results.
Always derive the dimensions from the referenced ranges using ROWS and COLUMNS where possible.
Note : If the LAMBDA inside MAKEARRAY uses INDEX to fetch from ranges, ensure that the row and column indices passed to INDEX never exceed the bounds of those ranges.
9.2. Incorrect LAMBDA parameter order.
Inside MAKEARRAY, the LAMBDA must accept parameters in the order (row, column).
If you reverse them, formulas referencing row based or column based logic will behave incorrectly.
When in doubt, test the LAMBDA with a very small array, for example 2x2, and verify each cell’s calculation manually.
9.3. Using relative references incorrectly.
Inside the LAMBDA, use absolute or named references for external inputs.
Do not rely on relative references that assume a particular anchor cell for the dynamic array, because the spilled range can start in different locations if the formula is moved or restructured.
9.4. Debugging with helper generators.
One practical strategy for debugging complex MAKEARRAY formulas is to create a temporary helper generator that outputs intermediate values such as row indices, column indices, or intermediate calculations.
=MAKEARRAY( 5, 5, LAMBDA(r, c, r & ":" & c) ) Once you confirm that indexing behaves as expected, replace the expression in the LAMBDA with the final logic.
FAQ
Which Excel versions support the MAKEARRAY function.
The Excel MAKEARRAY function is available in Microsoft 365 versions that support dynamic arrays and the LAMBDA function, including Excel for Microsoft 365, Excel for the web, and recent Insider builds.
Perpetual versions such as Excel 2016 or Excel 2019 do not support MAKEARRAY.
How is MAKEARRAY different from SEQUENCE.
SEQUENCE generates arrays of sequential numbers with fixed patterns, while MAKEARRAY is a general purpose array generator.
With MAKEARRAY, you define a custom LAMBDA that can output any expression, including non sequential numbers, text, or logic based on external data.
In short, SEQUENCE is specialized, and MAKEARRAY is flexible and programmable.
Can I reuse the same LAMBDA used in MAKEARRAY in other formulas.
Yes.
You can define a named LAMBDA in the Name Manager and then call it inside MAKEARRAY, passing row and column indices as arguments.
This promotes reuse and simplifies maintenance when building large models based on dynamic array formulas.
How do I optimize performance when MAKEARRAY generates a large array.
Use LET to cache repeated calculations, avoid unnecessary volatile functions, and align the array dimensions with actual data sizes.
If the model remains slow, experiment with splitting one large generator into several smaller arrays and avoid nesting too many complex functions inside a single LAMBDA.
Why does my MAKEARRAY formula return #CALC errors.
#CALC errors usually indicate that the LAMBDA expression failed for at least one cell, often due to out of range indices, division by zero, or incorrect argument types.
To troubleshoot, simplify the LAMBDA temporarily, check intermediate values, and confirm that the rows and columns arguments match the sizes of any referenced ranges.