Cap rate (short for capitalization rate) is a property's annual net operating income divided by its purchase price or current value, expressed as a percentage. It matters because it lets you compare the income potential of different properties on a level playing field, without factoring in how each one is financed.
What Cap Rate Is and Why It Matters
Cap rate answers a simple question: if you paid cash for this property today, what percentage return would its operating income alone generate in a year? It strips out your mortgage, so it's really a measure of the property's own earning power, not your personal return on the deal.
Investors use cap rate to quickly compare properties of different sizes, prices, and locations. A duplex and a small apartment building don't have much in common on the surface, but their cap rates can be lined up side by side because the math is the same: income over price.
Because cap rate ignores financing, it's especially useful early in a search, when you're screening a list of listings and want a fast way to rank them before digging into the details.
How to Calculate Cap Rate
The formula is straightforward: take the property's net operating income (NOI) for a year and divide it by the purchase price or current market value, then multiply by 100 to get a percentage.
Net operating income is the income a property produces after operating expenses, but before your mortgage payment, income taxes, and depreciation. That's what makes cap rate different from cash flow, which does account for the mortgage.
- •Step 1: Estimate the property's gross rental income for the year.
- •Step 2: Subtract realistic operating expenses — property taxes, insurance, maintenance, management, and a vacancy allowance.
- •Step 3: The result is net operating income (NOI).
- •Step 4: Divide NOI by the purchase price (or appraised value) and multiply by 100.
- •Step 5: Compare that percentage against similar properties or your own target to see how it stacks up.
Cap Rate vs Other Metrics
Cap rate is one tool among several, and it's easy to mix it up with related numbers. The table below lays out how it differs from a few metrics you'll run into constantly when evaluating rentals.
| Metric | What it measures | Accounts for financing? | Best used for |
|---|---|---|---|
| Cap rate | NOI as a percent of price or value | No | Comparing properties quickly, regardless of how they're financed |
| Cash flow | Money left over after all expenses and the mortgage payment | Yes | Understanding monthly income once you own the property |
| Cash-on-cash return | Annual cash flow as a percent of actual cash invested | Yes | Measuring return on your specific down payment and costs |
| DSCR | NOI divided by the annual mortgage payment | Yes | Checking whether income covers debt, often required by lenders |
Trade-offs and Pitfalls
Cap rate is useful, but it has real limits. Because it leaves out financing, two properties with identical cap rates can produce very different cash flow once you factor in different down payments, interest rates, and loan terms.
Cap rate is also only as reliable as the NOI estimate behind it. If expenses are underestimated or a vacancy allowance is skipped, the resulting cap rate will look better than the property actually performs. Sellers sometimes market an optimistic cap rate using thin expense assumptions, so it's worth recalculating the number yourself with your own, more conservative figures.
It's also not a stand-alone decision tool. Pairing cap rate with quick screens like the 1% rule, running your own cash flow projection, and checking debt coverage with DSCR gives a much fuller picture than any single number can.
Practical Takeaway
Use cap rate as a first filter, not a final verdict. It's a fast way to rank a batch of listings and flag which ones deserve a closer look, especially when you're comparing properties across different markets or price points.
Once a property clears that first screen, move on to the numbers that reflect your actual financing: cash flow, cash-on-cash return, and DSCR. Together, these metrics tell you not just what the property can earn, but what it will actually put in your pocket after your loan is factored in.
Frequently asked questions
What is a good cap rate?
There's no single cap rate that's universally good or bad; it depends on the market, property type, and how much risk and management effort you're willing to take on. Rather than chasing a specific number, compare a property's cap rate to similar properties in the same area to see how it stacks up.
Does cap rate include the mortgage payment?
No. Cap rate is based on net operating income, which is calculated before any mortgage payment, income taxes, or depreciation. That's what makes it useful for comparing properties independent of how each buyer finances them.
Is cap rate the same as return on investment?
Not exactly. Cap rate measures the property's own earning power relative to its price, while your actual return on investment depends on your down payment, loan terms, and cash flow, which cash-on-cash return captures more directly.
Can cap rate be used for single-family rentals?
Yes, though it's more commonly discussed for multifamily and commercial properties. For single-family rentals, many investors lean more heavily on cash flow and cash-on-cash return, then use cap rate as a secondary check.
How this post was made: the figures above come from OnOffDeals’ own market-scan data (refreshed roughly monthly); the draft was written with AI assistance and checked against that data before publishing. Everything here is an estimate to help screen deals, not financial advice.
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