Updated September 2026
Cap rate — net operating income divided by purchase price — is one of the fastest ways to compare rental properties, which is exactly why it gets over-relied on. It answers one specific question well ("how does this property's income compare to its price, independent of financing?") and answers several other important questions not at all. Here's what it leaves out.
Cap rate is calculated on NOI over price, with no mortgage anywhere in the formula. That's a deliberate design choice — it's what lets you compare a property you'd buy in cash against one you'd finance at 80% leverage on equal footing. But it also means cap rate tells you nothing about whether the deal actually cash flows for you, at your specific down payment and interest rate. Two investors can look at the identical property, see the identical cap rate, and end up with completely different monthly cash flow because their financing differs. That's what cash-on-cash return is for — always look at both, not one instead of the other.
Cap rate is computed from one year of NOI (or a trailing-twelve-month figure) at the purchase price. It says nothing about whether that income is growing, flat, or about to drop because a major tenant is leaving or a below-market lease is about to renew at a big jump. A property with a temporarily inflated NOI — say, deferred maintenance that's about to become a large expense, or a rent roll padded by a lease expiring next quarter — can show an attractive cap rate today and a much worse one in twelve months.
NOI subtracts operating expenses but not big, lumpy capital costs — a new roof, HVAC replacement, or foundation repair. A property with a deferred-maintenance backlog can post a cap rate that looks better than a well-maintained comparable simply because the capex hasn't hit the books yet. When comparing two properties on cap rate alone, a substantially older building or one with visible deferred maintenance deserves a mental discount that the raw percentage won't apply for you.
Cap rate and perceived risk move together in the market: properties in less stable neighborhoods, weaker rent-growth markets, older buildings, or markets with landlord-unfriendly regulation typically trade at higher cap rates, because buyers demand more income relative to price to compensate for that risk. A cap rate that looks unusually high compared to similar properties nearby is a prompt to ask why — not an automatic sign of an underpriced deal. Likewise a very low cap rate in a strong, low-vacancy market with long-run appreciation potential isn't necessarily overpriced; the market may simply be pricing in lower risk and future rent growth that a single-year NOI snapshot doesn't capture.
Total real estate return has three components most investors care about: cash flow, appreciation, and tax benefits (including depreciation). Cap rate only reflects the income component, measured against today's price. A property with a modest cap rate in a market with strong historical appreciation can still be the better long-run investment than a higher-cap-rate property in a stagnant market — cap rate just can't tell you which, because appreciation isn't part of its formula.
Cap rate is at its best for quickly screening comparable properties in the same market and asset class — apples-to-apples income-to-price comparisons where financing, condition, and location are roughly similar. It's at its weakest as a stand-alone "is this a good deal" signal across very different markets, property ages, or risk profiles. Run the calculator for both cap rate and cash-on-cash return on any property you're evaluating, and treat a cap rate that's notably above or below comparable listings as a question to investigate (what's driving it?), not an answer on its own.
Is there a "good" cap rate number? It depends entirely on the market, asset class, and risk profile — a cap rate considered strong in one metro can be mediocre in another. Compare against similar properties in the same submarket rather than a single universal benchmark.
Why does my cap rate differ from what a listing advertises? Listing cap rates sometimes use optimistic (pro forma) rent and expense assumptions rather than actual trailing performance. Recompute it yourself in the calculator using verified rent-roll and expense figures before trusting a marketed number.
Should I ever choose a lower cap rate deal over a higher one? Yes — if the lower-cap-rate property is in a market or condition where you have more confidence in income durability, appreciation, or lower capex risk. Cap rate is one input, not the whole decision.
This page is educational only, not investment advice. Verify all figures independently and consult a qualified real estate or financial professional before making a purchase decision.