How our Monte Carlo simulation works

Most rental property calculators give you one cash flow number, one cap rate, one IRR — all built on assumptions you typed in as if they were certain. But rent growth, vacancy, and appreciation are never exactly what you assumed; they drift, sometimes a little, sometimes a lot. A single-point estimate hides that uncertainty instead of showing it to you.

Instead of running your numbers once, Monte Estate runs the same deal 10,000 times, nudging appreciation, rent growth, and vacancy by a different realistic amount each time. Every trial reuses the exact same cash flow, cap rate, and IRR math as the main analysis — only the inputs vary. The result isn't a single guess; it's a full range of what could plausibly happen.

Three assumptions get varied per trial: appreciation rate, rent growth, and vacancy rate — the three inputs with the most real-world uncertainty over a multi-year hold. Each one is centered on your own estimate, with most trials landing close to it and a shrinking number landing further out in either direction — the same statistical pattern used in weather forecasting and financial risk modeling. Financing terms, expenses, and your holding period stay fixed at what you entered, since those are typically known in advance, not uncertain.

All 10,000 outcomes get sorted and summarized into three numbers: a worst case (5th percentile — only 5% of trials came in worse than this), a median (the 50th percentile — a realistic middle outcome), and a best case (95th percentile). We also surface the probability that a deal loses money over your holding period, so you're looking at actual risk, not just an upside case.

Every simulation starts from real numbers, not blind guesses — enter an address and Monte Estate pulls actual property details plus estimated value and rent to pre-fill your starting assumptions. Once the simulation runs, an AI-generated recommendation reads the full spread of outcomes and gives you a plain-language take on the deal.