What is a cap rate? A plain-language guide
Updated: October 12, 2026
The capitalization rate, almost always shortened to cap rate, is the most widely quoted yardstick for income property. It answers a simple question: if you paid the full price in cash, what share of that price would the property give back to you each year from its operations? Brokers put it at the top of listings, appraisers use it to estimate value, and investors and lenders use it to compare buildings that have little else in common.
This guide explains what the number means, how it is calculated, what it can and cannot tell you, and the mistakes that most often make a cap rate look better or worse than it really is.
The cap rate formula
A cap rate is the ratio between a property's yearly net operating income (NOI) and its price or current market value, expressed as a percentage:
Cap rate = net operating income ÷ property value × 100%
Net operating income is the rent and other income the property actually collects in a year, minus the costs of running it. Financing is left out on purpose: loan payments, interest and principal appear nowhere in the formula. That makes the cap rate a measure of the property itself, not of one particular buyer's loan.
Because the formula has only two inputs, it can be turned around. If you know the NOI and the cap rate that buyers expect, you can estimate the value: value = NOI ÷ cap rate. If you know the price and the cap rate, you can see the NOI the seller is implicitly promising: NOI = value × cap rate.
A simple example
Imagine a small apartment building offered for 640,000. Its four flats bring in 57,600 of rent a year in total, and the owner collects another 2,400 from parking and laundry machines. After allowing 3,000 for empty units and late payments, and paying 18,600 for property taxes, insurance, repairs, management and utilities, the building produces 38,400 of net operating income.
Cap rate = 38,400 ÷ 640,000 × 100% = 6.00%
In other words, a buyer paying cash would earn about 6.00% a year on the purchase price — before any change in the building's value, before income tax, and regardless of how the purchase is financed.
What goes into net operating income
A cap rate is only as reliable as the NOI behind it. A sound NOI starts with the rent the property can realistically collect, adds recurring extras such as parking, storage or laundry income, and subtracts an allowance for vacancy and tenants who do not pay. From that effective income you then deduct the yearly operating expenses, for example:
- Property taxes and building insurance
- Repairs, maintenance and cleaning
- Property management fees, even if you plan to manage the property yourself
- Utilities and service charges that the owner pays
- Advertising, letting fees and other costs of finding tenants
Mortgage payments, depreciation, your income tax and large one-off projects such as a new roof are not operating expenses. Our step-by-step guide to NOI goes through every line in detail.
Why investors use cap rates
Comparing different properties
Two buildings with different prices, sizes and rents are hard to compare directly. Converting both into a cap rate puts them on the same scale: a building at 7% produces more income for each unit of price than a building at 5%, whatever their size or location.
Estimating value
Appraisers using the income approach divide a property's stabilised NOI by the cap rates seen in recent sales of similar properties. If comparable buildings have sold at around 6% and a building produces 30,000 of NOI, a first estimate of its value is 500,000.
Reading the market
Across a whole market, cap rates show how buyers feel. When buyers compete for property and expect rents to rise, they accept less income for each unit of price, and cap rates fall. When money becomes more expensive or confidence drops, buyers demand more income, and cap rates rise.
Cap rate and value move in opposite directions
Because value equals NOI divided by the cap rate, a small change in the cap rate has a large effect on value. Take a property with 42,000 of NOI. At a 5% cap rate it is worth 840,000; at 6% it is worth 700,000; at 7% it is worth 600,000. A move of one percentage point, from 5% to 6%, cuts the value by a sixth even though the income has not changed at all.
This is why investors watch cap rates closely when interest rates change, and why the reverse calculation in our calculator is useful: enter a target cap rate and an NOI, and it shows the price that would deliver that return.
Cap rate compared with other return measures
The cap rate is a starting point, not a complete investment analysis. Related measures answer different questions:
| Measure | What it tells you |
|---|---|
| Cash-on-cash return | Your yearly cash flow after loan payments divided by the cash you put in. Unlike the cap rate, it depends on how much you borrow and at what interest rate. |
| Gross rent multiplier (GRM) | The price divided by the gross yearly income. It is quick to work out but ignores expenses and vacancy, so two properties with the same GRM can have very different cap rates. |
| Debt service coverage ratio (DSCR) | NOI divided by the yearly loan payments. Lenders use it to check that the income can comfortably carry the loan. |
| ROI and internal rate of return (IRR) | Returns over the whole holding period, including loan repayment, changes in value and the final sale. They rely on many more assumptions than a cap rate does. |
Our calculator shows the cap rate and GRM together and, once you add loan details, the cash flow, cash-on-cash return and DSCR as well.
What makes cap rates higher or lower
Cap rates differ from one property to the next for reasons that mostly come down to risk and expected growth:
- Interest rates. When borrowing costs and returns on safer investments rise, buyers usually demand more income from property, which pushes cap rates up. Falling rates tend to have the opposite effect, often with a delay.
- Location. Large cities with deep markets and strong job growth usually have lower cap rates than small towns or areas with a shrinking population.
- Property type. Flats, offices, shops, warehouses and hotels carry different risks and therefore trade at different cap rates, even in the same city.
- Age and condition. Buildings that will soon need major work usually sell at higher cap rates to compensate the buyer for the coming costs.
- Tenants and leases. Long leases with reliable tenants make income more secure and lower the cap rate; short leases or a single tenant with a weak payment record raise it.
- Growth expectations. Buyers accept a low cap rate today if they expect rents to grow quickly, and they demand a higher one when they expect rents to stall.
Limitations of the cap rate
A cap rate describes one year of income at one price. On its own, it does not show:
- How rents and expenses will develop in the coming years
- Large repairs and replacements that are due but do not appear in the accounts yet
- How a loan changes your own return
- Tax effects, which depend on your personal situation
- The time and effort needed to manage the property
For these reasons, the cap rate works best as a quick screen to decide which properties deserve a closer look, followed by a full cash-flow analysis of the ones that pass.
Common mistakes
- Relying on the seller's projections. Sales brochures often show a projected NOI based on full occupancy and future rents. Rebuild the NOI from actual rent records and expense bills.
- Leaving out vacancy. Assuming that every unit is always let and every tenant always pays inflates both NOI and the cap rate.
- Forgetting management costs. Even if you manage the property yourself, include a market-rate management fee, so that the result reflects the property and not your unpaid time.
- Deducting loan payments. Subtracting the mortgage from NOI mixes the property's return with your financing and makes comparisons meaningless.
- Comparing unlike properties. The cap rate of a new warehouse with a ten-year lease says little about an older block of flats in another city.
Key takeaways
- The cap rate is a property's yearly net operating income divided by its price or value.
- It ignores financing, so it measures the property rather than the deal.
- A higher cap rate means more income for the price, usually together with more risk.
- Value and cap rate move in opposite directions, and small changes in the rate move the value a lot.
- Use it to compare and screen properties, then check the full cash flow before you invest.