When you look at a rental property, the first number you’ll see on most listing sites is the “cap rate.” It is a quick way to compare the income‑generating potential of one asset to another, independent of financing. But a cap rate by itself tells you nothing about risk, market dynamics, or whether the deal is affordable for you.
In this guide we walk through the logic behind a “good” cap rate, illustrate every step with a single worked example, and give you a practical target you can apply the moment you start screening deals.
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What a cap rate measures
The capitalization rate, or cap rate, is simply the annual net operating income (NOI) divided by the purchase price. It is expressed as a percentage:
NOI is the cash the property generates after all operating expenses but before debt service, taxes, and capital expenditures. Because it strips out financing, the cap rate lets you compare apples‑to‑apples across properties with wildly different loan structures.
Our example property produces a monthly rent of $1,800, which yields an effective gross income (EGI) of $20,520 per year. After $8,088 of operating expenses, the NOI is $12,432 per year. Plug those numbers into the formula and you instantly see how price drives the cap rate.
The same income at four prices
Imagine you could buy the exact same property for four different price points. The income stays constant—$12,432 NOI—but the cap rate swings dramatically.
| Purchase Price | Cap Rate |
|---|---|
| $300,000 | 4.1 % |
| $250,000 | 5.0 % |
| $200,000 | 6.2 % |
| $180,000 | 6.9 % |
| Cap = NOI ÷ Price × 100 % | |
Yellow = inputs · Green = calculated
At $300 k the property yields a modest 4.1 % cap. Drop the price to $180 k and the same cash flow now represents a 6.9 % cap. The arithmetic is straightforward: $12,432 ÷ $300,000 = 0.0414 → 4.1 %; $12,432 ÷ $180,000 = 0.0691 → 6.9 %.
Cap rate ranges by market and property type
Investors often quote “typical” cap rates for a given city or asset class. The ranges we use in this guide are deliberately broad because we cannot cite external market studies:
- Expensive coastal or core urban markets: 4 %–5 %
- Many Midwest and Southern markets: 6 %–8 %
- Properties priced above 8 % usually signal higher risk, value‑add opportunities, or a distressed situation.
These brackets line up with the numbers in our example. The 4.1 % cap at $300 k falls squarely in the “expensive core” band, while the 6.2 % and 6.9 % caps belong to the “Midwest/South” band.
For a deeper dive into the mechanics of cap rates, see our Cap Rate Guide. If you need to verify the NOI calculation itself, our How to Calculate NOI article walks through every expense line.
The spread over your mortgage rate
Cap rate is only part of the story. What truly matters to a buyer is the spread between the cap rate and the cost of debt. In our example we assume a 7 % mortgage rate.
When the cap rate is below the mortgage rate, the investment is “negative leverage.” At a 5.0 % cap on a $250,000 purchase, the spread is –2.0 percentage points. That translates to a cash‑on‑cash return of –6.4 % and a debt service coverage ratio (DSCR) of 0.78, meaning the property does not generate enough cash to cover the loan payment.
At the 6.9 % cap on a $180,000 purchase, the spread shrinks to about –0.1 points. The cash‑on‑cash return hovers near zero and the DSCR approaches 1.0, indicating roughly break‑even leverage.
In practice, most buyers look for a cap rate that meets or exceeds their mortgage rate. The spread is the “risk premium” you earn for tying up capital.
Cap rate compression — what it means when rates fall
When market interest rates decline, mortgage rates tend to follow. As borrowing becomes cheaper, investors are willing to pay more for the same cash flow, pushing purchase prices up and cap rates down. This phenomenon is called cap‑rate compression.
Compression squeezes the spread between cap rate and debt cost. A property that once offered a 6.2 % cap at a 7 % mortgage (–0.8 point spread) might later trade at a 5.5 % cap with the same 7 % loan, widening the negative spread from –0.8 to –1.5 points.
Because the spread drives cash‑on‑cash and DSCR, compression can quickly turn a solid‑looking deal into a cash‑flow trap. The safest approach is to set a target cap that is comfortably above the highest mortgage rate you expect to encounter.
A practical target for a buyer
Our rule of thumb is simple: aim for a cap rate at or above your mortgage rate. In numeric terms, the spread should be zero or positive. Using the numbers above:
- At $300,000 (4.1 % cap) the spread versus a 7 % loan is –2.9 points → not a buy.
- At $250,000 (5.0 % cap) the spread is –2.0 points → still negative.
- At $200,000 (6.2 % cap) the spread is –0.8 points → borderline, but cash‑on‑cash remains negative.
- At $180,000 (6.9 % cap) the spread is –0.1 points → essentially break‑even; any further price reduction would create a positive spread.
Thus, in this scenario the only price that approaches a “good” cap rate is $180,000, where the cap rate almost matches the mortgage rate. If you could negotiate the price down a few thousand dollars, you would flip the spread positive and generate a modest cash‑on‑cash return.
When you start screening, plug the property’s NOI and your expected loan rate into a simple spreadsheet. Our free Lite version of the Real Estate Deal Analyzer does exactly that, showing cap, cash‑on‑cash, DSCR, and a quick 1 % rule check.
The verdict
Cap rate alone does not tell you whether a property is a good investment. You must compare the cap to your financing cost, understand market‑driven compression, and know where the property sits within typical regional ranges.
In our example, only the $180,000 price point comes close to meeting that rule. All higher prices generate negative leverage, meaning you would lose cash each month after debt service.
Common mistakes when using cap rates
- Assuming a higher cap rate always means a better deal without checking the spread to debt.
- Forgetting to adjust operating expenses for local market conditions.
- Using the listed rent instead of the effective gross income after vacancies and concessions.
- Ignoring cap‑rate compression trends that can erode your spread over time.
Run your own numbers
The workflow above is exactly what our spreadsheet automates. Start with the free Lite version of the Real Estate Deal Analyzer — the main analyzer sheet with cap rate, NOI, cash flow, cash‑on‑cash, DSCR and the 1% rule check. If you screen deals regularly, the Full version adds a sensitivity grid, a 5‑year projection with IRR, a BRRRR calculator, a 3‑deal comparison sheet, and a 15‑point due‑diligence checklist. Both are on the Real Estate Deal Analyzer page.
Lite first, free — the seven steps above on one sheet.
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This guide is an educational calculation aid, not financial, tax, or legal advice. Verify all figures against local data and consult licensed professionals before purchasing any property.