The capitalization rate is the return a property produces before any loan touches it: net operating income divided by value. Rent of 2,000 a month with 5% vacancy and 4,560 a year of operating expenses leaves an NOI of 18,240; on a value of 240,000 that is a cap rate of 7.60%. This calculator answers the question in all three directions — the cap rate a set of figures produces, the value an NOI justifies at the cap rate you demand, and the NOI (and the monthly rent behind it) that a given price requires at your target rate. Same formula, three different negotiations.
Building the NOI honestly
Start with the annual gross rent. Subtract vacancy and bad debt — even excellent rentals lose a few percent a year to gaps and arrears, and 5% is a kinder assumption than most streets deliver. Then subtract operating expenses: property tax, insurance, community or HOA fees, maintenance and repairs, and management if you will not manage it yourself. What remains is the NOI. Two things never enter it: the mortgage payment (debt is your financing choice, not the property’s performance) and income tax (it depends on you, not the building). Keep those out and cap rates stay comparable across properties and across buyers.
The three modes, worked
Cap rate: 2,000 a month rent, 5% vacancy, 4,560 expenses → NOI 18,240 on a 240,000 value = 7.60%. Value: the same NOI at a target cap rate of 6.5% supports a value of 280,615 — if the seller asks 240,000, the gap between the two numbers is the margin you are being offered for the risk. NOI needed: a 240,000 price at a 7.6% target demands exactly that 18,240 of NOI, which after the same expenses and vacancy works back to a required rent of 2,000 a month. If the achievable rent is 1,850, the price — not the spreadsheet — has to move.
Comparing cap rates without fooling yourself
A higher cap rate is not a better property; it is a cheaper price for the same income, usually because the income is riskier, the area is weaker, or the expenses you entered are optimistic. Cap rates compress in strong markets (buyers pay more per unit of NOI) and widen in weak ones, which makes last year’s benchmark a poor guide to this year’s deal. The figure is also only as honest as its NOI: an expense line that forgets management because “I’ll do it myself” prices your own labour at zero, and a vacancy of 0% is not a plan, it is a hope. Load realistic expenses, compare against cap rates of genuinely similar properties sold nearby, and use the reverse modes to turn the answer into an offer price and a minimum rent — the two numbers a negotiation actually runs on.
Cap rate is a snapshot, not a story
The calculation uses one year’s NOI, which makes it a photograph: it cannot show rents rising, a lease expiring, a roof ageing into a replacement, or the capital expenditure that never appears in operating expenses at all. Two properties at the same cap rate can be heading in opposite directions. That is why the cap rate works best as the middle step of three: the gross rent multiplier for a thirty-second screen, the cap rate for comparing income against price on equal terms, and a cash flow projection when you want to see what the loan, the reserves and the coming years do to the return. Each step forgives fewer illusions than the one before it, which is precisely why the middle step — this one — is where asking prices get negotiated down to numbers an income can defend.
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Versión en español: Calcular Cap Rate Inmobiliario Tasa de Capitalización: Rentabilidad Neta con Gastos y Vacancia · Gross Rent Multiplier Calculator · Rental Property Cash Flow Calculator.
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