The calculator said buy. We said walk. The client kept their $312,000.
A second-home buyer in a Sun Belt metro, ready to close on a condo the free tools scored as a solid rental. Here is what the algorithm's number missed — and why the number was never the thing worth paying for.
- Est. rent $2,650/mo (Rentometer)
- Airbnb: $58k/yr gross (AirDNA)
- Cash-on-cash ~9%
Every free calculator he tried agreed. On paper, an easy buy.
- Real defensible rent $2,180/mo (−18%)
- Airbnb: banned by the HOA + city permit cap
- True cash-on-cash −1%
The property doesn't cash-flow. The whole thesis rested on Airbnb income that was never legal here.
Three things no calculator can see
The comps were the wrong comps
Rentometer averaged the whole ZIP. But this unit was a ground-floor north-facing condo backing onto a service road — the three genuinely comparable units had rented for $2,050–$2,300, not $2,650. Pulling the real comps, not the algorithm's blend, took the defensible rent down $470/mo. That single correction turns a 9% return negative.
The Airbnb income was illegal
The AirDNA projection assumed the unit could operate as a short-term rental. The HOA's CC&Rs banned rentals under 30 days, and the city had already hit its short-term-rental permit cap. AirDNA has no way to know either. The entire upside case evaporated on one afternoon of reading covenants and a call to the city.
The costs were a fantasy
The listing's 'low HOA' was mid-special-assessment for a roof the reserve study said was five years overdue — another ~$180/mo coming. Insurance in the flood-adjacent tract quoted 40% over the buyer's placeholder. Real numbers, not defaults.
An AI can run the same arithmetic our calculator runs — instantly, for free. What it can't do is pull the right comps, read the HOA covenants, call the permit office, and tell you the number is wrong before you wire the deposit. That judgment is the deliverable. The client paid $249 and kept a $312,000 mistake in their pocket.
Have a property looked at →Details anonymised and figures adjusted to protect client confidentiality; representative of the analysis performed. An analysis is not an appraisal, valuation, or guarantee of outcome. Real estate carries risk.