Spreadsheet Sim overview
Spreadsheet Sim lets you run Monte Carlo simulations on existing Excel workbooks without rewriting your model.
What it does
You upload an .xlsx file, view it in the browser using IronCalc, mark uncertain cells as assumptions (assigning each a probability distribution), mark result cells as outputs, then run N simulation iterations. Each iteration samples new values for every assumption, recalculates the workbook, and records the output values. Results are visualized as histograms, one per output.
Who it's for
Anyone with a business model, financial projection, or engineering estimate in Excel who wants to understand the range of possible outcomes — not just a single point estimate.
note
Spreadsheet Sim requires a Pro plan. Free users see an upgrade prompt.
Key concepts
| Concept | Description |
|---|---|
| Assumption | An uncertain input cell. Each simulation iteration, this cell is overwritten with a value sampled from its distribution. |
| Output | A result cell or range. Its value is recorded after each iteration. |
| Iteration (rep) | One complete recalculation of the workbook with sampled assumption values. |
| Config | A saved set of assumptions and outputs for a workbook, so you don't have to re-configure each session. |
Next steps
- Setup — uploading a workbook and viewing it
- Assumptions — marking uncertain cells
- Running simulations — launching a run and polling for results
- Results — reading histograms and statistics