Excel SCAN Function in 2026: Master Running Calculations with Dynamic Arrays

If you've ever needed a running total, a cumulative average, or a step-by-step calculation that builds on the previous row, you've probably written complex helper columns or tangled array formulas. In 2026, Excel's SCAN function eliminates all of that complexity. As part of the modern dynamic array engine, SCAN lets you process data sequentially and accumulate results — all in a single formula. This guide explains how SCAN works, when to use it, and how it transforms advanced Excel analysis.

What Is the SCAN Function?

SCAN is a Lambda helper function introduced alongside REDUCE, MAP, BYROW, and BYCOL. While REDUCE collapses an array into a single value, SCAN returns all intermediate values along the way. Think of it as REDUCE with a memory — every step of the accumulation is preserved and returned as an output array.

The basic syntax is:

=SCAN(initial_value, array, lambda)

Where:

initial_value — the starting value for the accumulator (can be 0, blank, or any number)

array — the range or array of values to process one by one

lambda — a LAMBDA function with two parameters: the accumulator and the current value

Running Totals: The Classic Use Case

The most common use of SCAN is creating a running total without helper columns. Instead of copying a formula like =SUM($B$2:B2) down an entire column, you write one formula that spills results for every row.

Example: Running total of sales in column B

=SCAN(0, B2:B50, LAMBDA(acc, val, acc + val))

This single formula placed in one cell spills a running total for all 49 rows instantly. When new data is added to the table, the spill range updates automatically — no dragging formulas required.

Cumulative Averages and Running Counts

SCAN can also compute cumulative averages by tracking both the sum and the count of elements processed. However, Excel's SCAN only passes a single accumulator value. For multi-value accumulators, a common workaround is to encode both values into one number using a formula trick, or use SCAN alongside other functions.

A simpler approach for cumulative averages:

=SCAN(0, B2:B50, LAMBDA(acc, val, acc + val)) / SEQUENCE(ROWS(B2:B50))

This divides the running sum by the count of rows processed at each step, giving a clean cumulative average that updates dynamically.

Running Maximum and Minimum

Finding the running maximum — the highest value seen so far at each row — is another powerful SCAN use case. Previously this required a complex expanding range reference. Now:

=SCAN(B2, B2:B50, LAMBDA(acc, val, MAX(acc, val)))

Each output value represents the maximum seen from B2 up to that row. The equivalent for a running minimum uses MIN instead of MAX. These formulas are invaluable for tracking performance peaks, price maximums, or worst-case scenarios over time.

Inventory and Balance Tracking

SCAN is ideal for inventory tracking where each row represents a transaction and the balance is cumulative. Consider a sheet where column B is incoming stock and column C is outgoing stock:

=SCAN(0, B2:B50 – C2:C50, LAMBDA(acc, val, acc + val))

This produces the running stock balance after each transaction — without a single helper column. Add a starting balance by changing the initial_value from 0 to your opening inventory number.

Combining SCAN with IF for Conditional Accumulation

Not every row should be included in the accumulation. SCAN works elegantly with IF to apply conditional logic. For example, to build a running total only for rows where column D says 'Approved':

=SCAN(0, B2:B50, LAMBDA(acc, val, IF(D2:D50="Approved", acc + val, acc)))

Rows that don't meet the condition simply carry forward the previous accumulator value unchanged. This creates a conditional running total that responds dynamically to your data.

SCAN vs REDUCE: Knowing When to Use Each

Both SCAN and REDUCE process arrays iteratively, but they serve different purposes:

Use REDUCE when you need a single final result — the total sum, the final balance, or the concatenated string

Use SCAN when you need all intermediate values — running totals, cumulative metrics, or step-by-step progressions

SCAN always returns an array the same size as the input; REDUCE always returns a scalar

A good rule of thumb: if you want to see the journey, use SCAN. If you only care about the destination, use REDUCE.

Practical Business Applications in 2026

Here are some real-world scenarios where SCAN delivers immediate value:

Finance: Running cash flow balance across monthly transactions

Sales: Cumulative revenue toward quarterly targets

HR: Running headcount as employees join and leave

Project management: Accumulated hours against a project budget

Inventory: Stock level changes from daily receipts and shipments

Copilot and SCAN: Writing Formulas with AI

In 2026, Excel Copilot can help you build SCAN formulas from plain English. Simply describe what you need in the Copilot pane: 'Show me the running total of sales in column B starting from row 2.' Copilot will suggest the appropriate SCAN formula, explain each argument, and insert it directly into your selected cell. For complex conditional logic, describe the conditions and Copilot handles the LAMBDA construction — dramatically reducing the learning curve for new users.

Tips for Getting the Most from SCAN

Always define a meaningful initial_value — 0 for sums, a large number for running minimums, or the first data point

Use structured table references (Table1[Sales]) inside SCAN for automatic range expansion

Combine SCAN with IFERROR to handle blank or error cells gracefully

Wrap SCAN in XLOOKUP or INDEX to retrieve a specific cumulative value at a particular row

Test on small data ranges first, then expand the array reference once the logic is confirmed

Conclusion

Excel's SCAN function is one of the most underutilised tools in the modern dynamic array toolkit. Once you understand how it works, you'll find yourself reaching for it every time you need a running calculation, a cumulative metric, or a step-by-step progression through your data. Combined with Excel Copilot in 2026, SCAN formulas become even more accessible — letting business users of all skill levels harness the power of sequential array computation without writing a line of VBA.

Start by replacing your first helper-column running total with SCAN, and you'll immediately see why this function changes the way you think about Excel data processing.