A running product multiplies each value by all the ones before it — the multiplicative cousin of a running total. Perfect for chained growth factors, cumulative probabilities, and index numbers.
The example
Growth factors compound down the column.
| A | B | |
|---|---|---|
| 1 | Factor | Cumulative |
| 2 | 1.10 | 1.10 |
| 3 | 1.05 | 1.155 |
| 4 | 1.20 | 1.386 |
The formula
The formula:
How it works
How it works:
PRODUCT($B$2:B2)multiplies every value from the locked top cell through the current row.- The absolute start (
$B$2) and relative end (B2) make the range grow as you fill down. - Use it to compound growth factors (1.10, 1.05, …) into a cumulative index.
- For cumulative probability of independent events, multiply the per-event probabilities the same way.
From growth rates to factors: if your column holds percentage changes, convert first — =PRODUCT($B$2:B2 + 1) as an array, or add a helper column of 1 + rate. The final cumulative factor minus 1 is the total compounded change.
Try it: interactive demo
Growth factors (comma-separated).
Variations
Running total
Additive cousin:
From rates
Add 1 first:
Total change
Final factor:
Pitfalls & errors
A zero wipes it out. One zero in the range makes the whole cumulative product zero.
Lock the start. Forgetting the $ on the first cell breaks the expanding range.
Rates need +1. Multiply growth factors (1.1), not raw percentages (0.1).
Practice workbook
Frequently asked questions
How do I make a running product in Excel?
How is it different from a running total?
Why does my running product become zero?
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