What is a probabilistic business case? A probabilistic business case is a written justification for a proposed investment that reports its financial outcomes as ranges rather than single numbers. Instead of quoting one NPV figure, it uses Monte Carlo simulation to sample each uncertain input (revenue growth, cost inflation, adoption rate) across a plausible range, producing a distribution of possible NPVs. The result tells a decision-maker not only whether the case is favourable on average, but how often it fails under stress. This tool builds one in the browser: enter your options and assumptions, run 20,000 simulated trials, and download a six-section audit-ready PDF that captures the reasoning, the numbers, and the sensitivity of the recommendation to each assumption.
1Project context
2Options considered
| Option | One-line summary |
|---|
The first option labelled Do nothing is the baseline. The financial model below is for the option you recommend; the others are compared qualitatively in the PDF.
3Financial parameters
Discount rate reflects time value of money. Hurdle rate is the IRR threshold below which the project does not clear capital allocation.
4Costs (recommended option)
| Year | CapEx ($) | OpEx ($) |
|---|---|---|
| Year 0 (now) | ||
| Year 1 | ||
| Year 2 | ||
| Year 3 | ||
| Year 4 | ||
| Year 5 |
5Benefits (recommended option)
| Year | Financial benefit ($) |
|---|---|
| Year 1 | |
| Year 2 | |
| Year 3 | |
| Year 4 | |
| Year 5 |
| Benefit | Metric | Target by date |
|---|
6Uncertainty drivers
| Driver | Optimistic (%) | Most likely (%) | Pessimistic (%) |
|---|---|---|---|
| CapEx variance | |||
| Benefits realisation | |||
| OpEx variance |
Convention: pessimistic CapEx and OpEx are higher than base (positive %), pessimistic benefits are lower than base (negative %).
7Top risks
| Risk | Likelihood (%) | Impact ($) | Mitigation |
|---|
Compute the case
Press the button. We will run 20,000 Monte Carlo trials, compute NPV, IRR, payback and ROI, and rank your uncertainty drivers by impact.
Results
Probabilistic NPV (20,000 trials, Beta-PERT)
Sensitivity tornado — which driver moves NPV the most
Each bar shows the swing in NPV when that driver moves from optimistic to pessimistic, holding others at most-likely. The widest bar is your biggest exposure.
8Recommendation and decision record
Get the business case PDF
A six-section, audit-ready document with executive summary, options, financial analysis with sensitivity, risks, recommendation and decision record.