This deal cash flows... until rent drops 10%. Run a base, downside and stress case before you make an offer.
A single cash flow number tells you what happens if everything goes to plan. A stress test tells you what happens if it doesn't. Experienced investors run the same property at least three times:
You are not predicting that the stress case will happen. You are finding out how much room for error the deal has. Then add one more number: breakeven occupancy, the share of full rent you need to collect just to cover costs.
Downside: vacancy at least 10%, rent flat, taxes and insurance +10%. Stress: the downside case plus rent 10% lower and the interest rate +1 point. Assumes a 30-year fixed-rate loan. Estimates for educational purposes, not financial advice.
Stress test a real listing in seconds. In PropAnalyzer AI, open any address or ZIP code result, change the rent, rate or taxes, and watch cash flow, cap rate and the 0-100 AI score update live.
This is an illustrative example, not a real listing or market data. It is the calculator's default: a $300,000 single-family rental, 20% down ($60,000), a $240,000 loan at 7.0% over 30 years, $2,600 a month in rent, $3,600 a year in taxes, $1,800 in insurance, no HOA, 8% of rent for maintenance and CapEx, and 5% vacancy.
What it tells you: the base case looks fine, but the margin is thin. The downside case almost wipes out the cash flow, and in the stress case the property loses money even if it is rented every single month (breakeven occupancy above 100%). Whether that is acceptable depends on your reserves, how confident you are in the rent, and whether your rate is already locked. That is your call, not the calculator's.
Test the inputs you are least sure about first.
The biggest single input. Check it against nearby rentals before you trust it, then lower it 5-10% and see what is left. In PropAnalyzer AI, rent comps are pinned on a map with the median rent and range.
One empty month is about 8% of a year's rent. Use local experience where you have it, and test a higher number either way.
Both can change after you buy. Use the actual tax bill and a real insurance quote, not the seller's numbers, and test an increase.
If you haven't locked financing yet, a 1-point change moves the payment a lot: in the example above, 7% to 8% adds about $164 a month. This shows the mechanics only. It is not loan advice.
The calculator above is good for one property you already have numbers for. In the app you start from a real listing: search an address, or enter a ZIP code to get the top 3 AI-ranked deals, and the price, rent estimate and local market data are filled in for you.
Cash flow, cap rate and the score update live with each change, and you can re-run the AI analysis with your numbers. Every analysis is saved to your Analysis History. Prefer to do it by hand? The cash flow calculator shows the full formula, and the ARV calculator covers flips.
Run the same property three times. A base case with your realistic rent, vacancy and costs. A downside case with higher vacancy (for example 10%), rent that doesn't grow while taxes and insurance rise. And a stress case that adds lower rent (for example 10% below your estimate) and a higher interest rate (for example +1 point). If the deal only works in the base case, it has no margin for error.
Breakeven occupancy is the share of full rent you must collect to cover all operating costs and the mortgage payment. Breakeven occupancy = (operating expenses excluding vacancy + debt service) / gross potential rent. The lower it is, the more vacancy the property can absorb. Above 100% means the property loses money even when fully rented.
Yes. With Live Recalculation you can edit rent, price, down payment, interest rate, HOA and taxes on any property and watch cash flow, cap rate and the 0-100 AI score update, then re-run the AI analysis. To approximate higher vacancy, lower the rent input by the same percentage.
Free to download on iPhone & Android. Search an address or a ZIP code, then change any input and watch the score move.