Running revenue
=SCAN(0, C2:C, LAMBDA(acc, v, acc+v)) cumulative sums sales down the column.
What is SCAN in Google Sheets?
SCAN is like REDUCE but returns every intermediate accumulator in a spilled column. It powers running totals, cumulative text builds, and step-by-step counters without dragging cumulative formulas.
When to use it
Use SCAN for running balance columns, cumulative revenue, or showing how a fold evolves across a list.
When to skip it
Skip SCAN when you only need the final aggregate. REDUCE or SUM is simpler.
How it works
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1
Provide starting accumulator value matching the result type you need.
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2
Pass the array to walk through in order.
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3
Define LAMBDA(acc, value, next_acc) for each step.
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4
SCAN spills one row per array element with the accumulator after each step.
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5
Align output beside source data for chart-friendly running series.
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6
Guard blanks in LAMBDA so running math does not break mid-column.
Examples in Google Sheets
Running max
=SCAN(0, B2:B, LAMBDA(acc, v, MAX(acc, v))) tracks peak value seen so far.
Growing text log
=SCAN("", A2:A, LAMBDA(acc, v, acc & v & "; ")) builds a semicolon-separated trail.
Build this without starting from a blank cell
Use a Better Sheets tool for SCAN, then watch a walkthrough when you want the full pattern.
Better Sheets resources
Common mistakes
- Expecting SCAN to return one cell like REDUCE.
- Starting accumulator incompatible with later math, such as text plus number.
- Including header cell in the scanned range.
- Using SCAN for simple running sum when a basic cumulative reference would confuse fewer teammates.
- Not leaving spill room beside long columns.
Frequently asked questions
- SCAN vs running SUM?
- SCAN with LAMBDA allows custom rules each step, not only addition.
- SCAN output size?
- Same length as the input array, one accumulator per element.
- SCAN and charts?
- Pair running SCAN output with dates for line charts of cumulative metrics.
- SCAN vs REDUCE?
- SCAN shows all steps. REDUCE shows only the end.
- Blank cells in SCAN?
- Treat explicitly in LAMBDA or FILTER blanks first.
- Can SCAN go horizontal?
- Input orientation follows your array; output spills down by default.
- SCAN performance?
- Long arrays with heavy LAMBDA slow recalc like other array helpers.
Related Tutorials
Watch how SCAN works
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Related blog posts
Guides that explain SCAN in more depth.
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Read post →Related glossary terms
REDUCE
REDUCE walks an array left to right, carrying an accumulator value updated by a LAMBDA on each step. It can implement custom aggregates, text joins with rules, or conditional running logic that SUM alone cannot express.
Read guide →MAP
MAP walks aligned arrays element by element and applies a LAMBDA to each position. Pass one array for unary transforms or several arrays for element-wise combinations. It is the modern replacement for many ARRAYFORMULA column operations.
Read guide →LAMBDA
LAMBDA defines an anonymous function inside a formula. You name parameters, write the calculation, then pass arguments when you call it. Combined with MAP, BYROW, or a named LAMBDA in the Name manager, it replaces fragile copy-paste logic across big tables.
Read guide →MAKEARRAY
MAKEARRAY creates a grid of specified height and width, computing each cell with a LAMBDA that receives row and column indexes. It builds lookup tables, sensitivity matrices, and coordinate-driven templates without manual fill.
Read guide →Done reading about SCAN?
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