What a cap rate actually tells you about a rental property
The listing said 8.2%. I ran the numbers myself and got 5.9%. Same duplex, same asking price, same week. The difference was $4,800 a year in expenses the seller had quietly left out — property management, a water bill the tenant wasn't paying, and a roof repair amortized over nothing.
That gap is the entire story of cap rates. It's the single most quoted number in rental investing, and one of the most abused. Understanding cap rates for rental properties isn't hard math. It's knowing which inputs are honest and which are decoration.
Here's the core idea: a cap rate measures the unleveraged return a property produces in a single year, based on what it actually earns after operating costs. It ignores your mortgage. It ignores appreciation. It ignores your tax situation. That narrowness is a feature — you can compare a strip mall in Ohio to a fourplex in Phoenix on the same scale.
Net operating income divided by property value (or purchase price). That's it. A property generating $42,000 in NOI and priced at $600,000 carries a 7% cap rate.
Key Takeaways
- A cap rate is NOI ÷ price. It measures unleveraged annual yield and nothing else.
- "Good" is relative: 5% is respectable in a coastal metro, alarming in a small Midwest city.
- The 7% rule and the 2% rule are fast screening tools, not valuation methods.
- Cap rate compression means buyers accept lower yields — usually a bet on appreciation or cheaper debt.
- Sellers manipulate the numerator. Always rebuild NOI from tax returns, not the offering memo.
- Cap rate says nothing about your actual cash flow once a mortgage is in play.
The cap rate formula, and where it breaks
The formula is clean. The inputs are where people get sloppy.
Building NOI correctly
NOI starts with gross rental income, then subtracts everything needed to keep the building running: property taxes, insurance, maintenance, management fees, HOA dues, utilities you cover, and a vacancy allowance. What it does not subtract is your mortgage payment, capital expenditures on a major renovation, or income tax. Those sit below the line.
Two mistakes show up constantly.
The first is forgetting vacancy. A seller will hand you a rent roll showing every unit leased. Fine — but units turn over. In my own small portfolio, I plan for about one vacant month per unit every eighteen months, so I bake roughly 5–6% of gross rent into the model. Skip that line and your NOI looks bigger than reality will ever deliver.
The second is calling deferred maintenance a "capital expense" and pushing it out of the picture entirely. A roof that will need replacing in three years is a real cost of owning that building this year, whether or not the invoice lands in your inbox today.
What the formula deliberately ignores
Financing. This trips up new investors more than anything else. Two buyers can look at the same 6% cap property and have completely different outcomes, because one pays cash and the other uses a 75% loan-to-value mortgage at a rate that eats most of the yield. The cap rate is identical. The cash-on-cash return is not.
Appreciation is the other blind spot. A 4% cap in a neighborhood where values climb 6% a year can beat an 8% cap in a stagnant town. The cap rate doesn't know that. You do.
What is a good cap rate on a rental property?
There is no universal number, and anyone who gives you one is selling something. What counts as good depends entirely on what you're buying and where.
Markets price risk through the cap rate. A newer apartment building in a supply-constrained coastal metro trades at a lower cap because buyers are confident about rent growth and resale value. The same money in a tertiary market buys a higher cap because the risk of a soft rental season is real. Roughly speaking, you'll see single-family rentals in strong metros pricing in the 4–6% range, while smaller markets and older stock drift toward 7–9%. Multifamily on the coasts sits even lower.
What does a 7.5% cap rate mean?
A 7.5% cap rate means the property produces $7.50 of net operating income for every $100 of purchase price, before any mortgage. On a $500,000 building, that's $37,500 in annual NOI.
What that number means for you is contextual. In a market where comparable properties trade at 6%, a 7.5% cap is either a bargain or a warning — often the latter. Higher caps usually signal something: an aging roof, a rent roll that's above market, a neighborhood with softening demand, or a seller who needs liquidity fast. If a deal looks too good, dig into why before you celebrate.
I passed on a 9% cap duplex two years ago and still think about it. Turned out the tenant had been there fourteen years at a rent 40% below market, and the seller had priced the building off "market rent" that nobody was paying. The listing cap was fiction.
What is the 7% rule for rental property, and what is the 2% rule?
These are screening shortcuts, not valuations. Use them to filter a list of fifty properties down to five you'll actually analyze.
The 7% rule is loose: aim for a property whose net operating income lands around 7% of the purchase price. It's a rule of thumb for markets where 7% is a reasonable target — mostly mid-size cities with balanced supply and demand. In San Francisco or Boston, no deal will ever hit it, and that's fine; the rule simply doesn't apply there.
The 2% rule is stricter and older: monthly rent should equal at least 2% of the purchase price. A $200,000 house would need $4,000 in monthly rent. You will not find that in any major metro. You might find it in pockets of the Midwest or South, usually in neighborhoods where the vacancy risk is higher and the tenant pool thinner. The rule survives mostly because it forces you to look at cheap, high-yield properties — a useful discipline even when the number itself is unattainable.
The honest take: these rules tell you what kind of market you're in, not whether a specific deal is good. When I screen listings, I use a rough 6% floor as a filter and then stop applying rules entirely. Every property past that filter gets a full rebuild of its income and expenses. The rules earned their place as a starting point. They have no place in a final decision.
Cap rate vs. the metrics it gets confused with
People mix these up constantly, and the confusion costs them money.
| Metric | What it measures | Includes financing? | Best used for |
|---|---|---|---|
| Cap rate | Unleveraged annual yield on price | No | Comparing properties across markets |
| Cash-on-cash return | Annual cash flow ÷ cash invested | Yes | Judging a specific deal with your specific loan |
| Gross rent multiplier | Price ÷ annual gross rent | No | Quick screening when expenses are unknown |
| IRR | Total return including sale proceeds | Yes | Full hold-period projections |
The practical difference between cap rate and cash-on-cash is enormous in a high-rate environment. A property at a 6% cap financed at 7% interest on 75% of the price produces negative leverage — you're paying more for the debt than the asset yields. That deal can still work if rents grow and you refinance later, but it will bleed cash every month until then. The cap rate never warns you. Cash-on-cash does.
Going-in vs. exit cap rate
Something worth knowing before you build any projection: the cap rate you buy at (going-in) and the cap rate you sell at (exit) are almost never the same. If you buy at 6% and sell five years later at 7%, your sale price drops even if NOI grew — the market is applying a higher yield to the same income stream.
Brokers love to model a flat or slightly lower exit cap because it inflates the projected return. In a rising-rate stretch like the one we've been through, exit caps have mostly moved up, not down. When I build a model, I assume the exit cap will be at least 50 basis points higher than my going-in rate. If the deal only works with a compressed exit, it doesn't work.
Common questions from first-time buyers
Where do I find reliable cap rate data for my market?
Local commercial brokers publish quarterly reports by asset class and submarket. For single-family rentals, they're less useful — you're better off calling a few property managers and asking what yields buyers are actually accepting right now. Numbers from people writing checks beat numbers from a report every time.
Does a high cap rate always mean a bad deal?
No, but it usually means something needs explaining. High caps cluster around older buildings, weaker rental markets, above-market rents, and sellers under pressure. Any one of those can be an opportunity if you understand it. Go in with your eyes open and you'll do fine.
The part most people skip
Here's what three years of doing this taught me the hard way: the cap rate is a great sorting tool and a terrible decision tool. It gets you from five hundred properties to five. It does not tell you whether you'll sleep well at night owning the one you pick.
What actually decides your outcome is the stuff below the cap rate line. Your loan terms. Your reserve fund. Whether the roof holds. Whether the market you bought into keeps adding jobs or starts losing them. The cap rate is the headline. The details are the story.
So use it. Just don't mistake it for the whole picture.
