Running Product Calculator

A running product is what you compute when you want the cumulative effect of repeated multiplication — every value multiplies into the running total, instead of adding. The arithmetic is slightly more delicate than the running sum because products blow up fast, react violently to inputs near zero, and lose precision in regular floats after a handful of factors. For those reasons, the running product is a less frequent ask but a more interesting one.

Running Product Calculator handles the multiplication correctly, including BigInt precision for arbitrarily long lists of integers, sign-flip tracking, magnitude reporting and zero-collapse detection. Paste integers or floats, set the precision mode, and get a clean table of every running-product value along with statistics, geometric mean and a chart view that scales to wide ranges via a log axis.

Underneath the buttons is the small amount of information the system actually requires — what a running product represents, why zeros matter, what sign flips imply — plus practical guidance on how to interpret the result. Everything runs in your browser; nothing is uploaded.

• Any input list: Paste integers or floats, one per line, comma-separated, space-separated or any mix. Blanks are ignored.
• BigInt precision: Integer arithmetic preserves full precision across arbitrarily long lists. Float mode is available for fractional inputs.
• Zero-collapse detection: Flags the first zero and tells you how many subsequent steps are affected.
• Sign flip tracking: Counts negative-input sign flips and reports the sign of the final running product.
• Magnitude tracking: Reports the order-of-magnitude at every step, useful when the running product is too large to display directly.
• Geometric mean: Computes the multiplicative counterpart of the arithmetic mean for the same list.
• Line chart view: Visualise the running product over time, with an optional logarithmic axis for very wide ranges.
• Three export formats: CSV (running product), JSON array, and a plain text list with original value and running product together.
• Copy or download: Take what you compute without leaving the browser, with nothing uploaded to any server.

1. Pick the precision mode. Integer for whole-number inputs (BigInt), Float for fractional inputs.
2. Paste your numbers. One per line is the most reliable input; comma-separated or space-separated also work.
3. Set the display format. Plain numbers for small products, scientific notation for very large values.
4. Read the per-step output. Every running product is shown alongside the input that produced it.
5. Check the summary. Total product, count, geometric mean, sign flips, zero-collapse step and peak magnitude reported.
6. Open the chart view. A line view of the running product — toggle the log axis for very wide ranges.
7. Copy or download the result. CSV for spreadsheets, JSON for code, plain text for documentation.

Example 1 — Factorials. Paste the integers 1 through 10. The last running product is 10 factorial — 3,628,800. Use BigInt mode to push that further; 20 factorial is 2,432,902,008,176,640,000.

Example 2 — Compound growth. Paste 12 monthly growth rates as decimals like 1.05, 1.04, 1.08, etc. The final running product is the cumulative growth factor — subtract 1 and multiply by 100 to get the total percentage growth.

Example 3 — Probability product. Paste probabilities like 0.95, 0.92, 0.88. The running product is the cumulative probability of all independent events happening together — useful for reliability calculations.

Example 4 — Geometric series scaling. Paste a sequence of scaling factors and the running product is the cumulative scale at every step.

Example 5 — Detecting zero in the data. A zero somewhere in the list collapses everything to zero, which is usually a data error. The calculator flags the first zero so you can correct it.

• Stop writing throwaway scripts: Get a clean running-product table in one click from any list of numbers.
• Preserve precision: BigInt mode keeps the full value even for very long lists of integers.
• Catch zero-collapse early: The first zero is flagged, so data errors are visible immediately.
• Track magnitude separately: The order-of-magnitude at every step works even when the value itself is unmanageable.
• Match any consumer: CSV for spreadsheets, JSON for code, plain text for documentation.
• Free and private: No account, no watermark, nothing uploaded.