Real estate is one of the few asset classes where otherwise sophisticated investors routinely make decisions based on vibes. They run discounted cash flow analysis on a stock, then buy a $350,000 rental property because the rent "covers the mortgage." That gap—between the rigor applied to paper assets and the casual math applied to physical ones—is where most rental property returns quietly leak away.
This guide walks through the five metrics every rental property investor should understand, how to calculate each, what numbers to target, and how leverage, taxes, and exit strategy change the picture. None of this is exotic—it's the basic arithmetic that separates investors who compound wealth from those who own a second job.
The five core metrics
Different metrics answer different questions. Use them together, not in isolation.
- Cap rate—unleveraged return on the property.
- Cash-on-cash return—return on the actual cash you invested.
- IRR—time-weighted return over the entire holding period, including the sale.
- 1% rule—quick screen for whether a property is worth analyzing.
- 50% rule—rough estimate of operating expenses.
Cap rate: the unleveraged yield
Cap rate (capitalization rate) is the property's net operating income (NOI) divided by its current market value or purchase price. It measures the unleveraged return—what you'd earn if you paid all cash.
Cap rate = Net Operating Income ÷ Property Value
NOI is gross rental income minus operating expenses (property taxes, insurance, management, maintenance, vacancy, repairs), excluding the mortgage payment and capital expenditures. The mortgage payment is a financing cost, not an operating cost.
Worked example
A duplex generates $3,200/month in rent ($38,400/year). Operating expenses run about $17,400/year (taxes, insurance, vacancy, management, repairs). NOI = $38,400 − $17,400 = $21,000. If you paid $300,000, the cap rate is $21,000 ÷ $300,000 = 7.0%.
What's a "good" cap rate?
Cap rates are market- and asset-specific. There's no universal right answer—only what's appropriate for the risk profile:
- 3–5%—premium urban multifamily (Manhattan, San Francisco), where appreciation is the main driver.
- 5–7%—stable suburban rentals in growing Sun Belt metros.
- 7–9%—secondary markets, Class B/C properties, working-class neighborhoods.
- 9–12%+—tertiary markets, distressed properties, higher-risk tenant profiles.
Higher cap rates compensate for higher risk—economic volatility, tenant turnover, deferred maintenance, or slower appreciation. A 10% cap rate in a declining Rust Belt town is not "better" than a 5% cap rate in Austin; it's a different risk-reward profile.
Cash-on-cash return: the leveraged yield
Cash-on-cash return measures the actual cash you put in your pocket each year relative to the cash you invested. This is the metric most leveraged investors care about most, because it answers "what am I earning on my actual money?"
Cash-on-cash return = Annual pre-tax cash flow ÷ Total cash invested
Annual cash flow = NOI − mortgage payments − capital expenditures. Total cash invested = down payment + closing costs + rehab costs.
Worked example
Same $300,000 duplex. You put 25% down ($75,000) plus $8,000 in closing costs = $83,000 cash invested. NOI is $21,000. Your mortgage (75% LTV at 6.5%, 30-year amortization) is about $14,200/year. Cash flow = $21,000 − $14,200 = $6,800. Cash-on-cash return = $6,800 ÷ $83,000 = 8.2%.
Note how leverage increased your cash-on-cash return from 7.0% (unleveraged cap rate) to 8.2%—this is the magic of positive leverage. It works because your mortgage constant (annual debt service ÷ loan amount) is 6.3%, which is below the 7.0% cap rate. Whenever cap rate exceeds the mortgage constant, leverage boosts returns.
Flip the math: if rates were 8.5% (mortgage constant around 8.3%), your cash flow would drop and cash-on-cash would fall below the unleveraged cap rate. That's negative leverage—borrowing at a higher rate than the asset yields. Many investors who bought in 2022–2023 with rates in the 7s are now experiencing this firsthand.
IRR: the time-weighted return
Internal Rate of Return (IRR) accounts for the timing of every cash flow—inflows (rent, sale proceeds) and outflows (purchase, repairs, mortgage payments)—over the entire holding period. It's the most complete measure of return for an investment you'll eventually sell.
IRR captures what cap rate and cash-on-cash miss: appreciation at sale, loan paydown, and the time value of money. A property with a mediocre 5% cap rate but 5% annual appreciation can produce a 12–15% IRR over a 10-year hold—beating most stocks.
Worked example
You buy the $300,000 duplex, put $83,000 down, receive $6,800/year in cash flow for 10 years, then sell for $400,000 (about 3% annual appreciation). At sale, you pay 6% commission ($24,000) and pay off the remaining mortgage balance of about $203,000. Net sale proceeds: $400,000 − $24,000 − $203,000 = $173,000.
Your IRR is the discount rate that makes the present value of all those cash flows equal to your $83,000 investment. In this case, IRR works out to roughly 12.5%—a strong return driven primarily by appreciation and loan paydown, not operating cash flow.
This is why IRR is the metric serious investors use to compare deals. A property that cash-flows poorly but appreciates strongly can outperform one with great cash flow but no appreciation.
The 1% rule: a quick screen
The 1% rule says monthly rent should be at least 1% of the purchase price. A $200,000 property should rent for $2,000/month. A $300,000 property for $3,000/month.
This is not a guarantee of profitability—it's a screen to decide whether a property is worth analyzing. Properties meeting the 1% rule typically have decent cap rates and cash-on-cash returns in normal interest rate environments.
In high-cost markets, the 1% rule is rarely achievable. A $700,000 condo in Los Angeles might rent for $3,500/month—0.5% of price. Investors in these markets rely on appreciation, not cash flow. In affordable Midwest markets, properties often exceed the 1% rule, sometimes hitting 1.5–2%.
The 50% rule: a sanity check
The 50% rule says operating expenses (excluding mortgage) will consume about 50% of gross rent over the long term. The other 50% goes to the mortgage and (whatever's left) to cash flow.
This is a rough estimate—real expenses vary from 35% (new construction, low-tax states) to 60%+ (older properties, high-tax states, high-turnover tenant bases). But for a quick screen, assume 50% unless you have reason to think otherwise.
If gross rent is $2,500/month, expect ~$1,250 to cover operating expenses, leaving ~$1,250 for mortgage and profit. If your mortgage payment is $1,400/month, you're negative. If it's $1,000/month, you have $250/month positive cash flow.
Tax benefits: depreciation and 1031 exchanges
Depreciation
The IRS lets you depreciate the building (not the land) over 27.5 years for residential rental property. On a $300,000 property with 80% building value ($240,000), that's about $8,700/year in non-cash depreciation expense that shelters rental income from taxes.
If your taxable rental income is $6,800 (cash flow) but you have $8,700 in depreciation, you might show a $1,900 paper loss on your tax return while pocketing $6,800 in cash. This is one of real estate's most powerful benefits—though depreciation recapture applies when you sell.
1031 exchanges
Section 1031 of the tax code lets you defer capital gains taxes when you sell a rental property, provided you reinvest the proceeds into another investment property within specific timelines (45 days to identify, 180 days to close). Done repeatedly over a career, 1031 exchanges can defer hundreds of thousands in taxes—effectively giving you an interest-free loan from the IRS to compound wealth.
1031s are complex and have strict rules. Use a qualified intermediary and a CPA who specializes in real estate. Mistakes can disqualify the exchange and trigger immediate tax bills.
Comparing strategies: buy-and-hold, fix-and-flip, BRRRR
Buy-and-hold
The classic strategy: buy a property, rent it out, hold for decades, let tenants pay down the mortgage, benefit from appreciation and tax advantages. Lower risk, slower wealth build, the most tax-efficient path.
Fix-and-flip
Buy distressed, renovate, sell for profit. Returns are taxed as ordinary income (or self-employment income), not capital gains. Risk is concentrated—mistakes in rehab budget or ARV (after-repair value) can wipe out a deal. Margins are typically 10–25% of ARV. Most successful flippers treat it as a full-time business, not an investment.
BRRRR (Buy, Rehab, Rent, Refinance, Repeat)
Buy a distressed property with cash or short-term financing, renovate, rent it out, then refinance with a long-term mortgage based on the new appraised value—pulling most or all of your initial capital back out. Repeat with the same capital. This is how investors scale from one property to ten without raising new equity each time.
BRRRR math requires the post-rehab appraised value to be high enough that a 70–75% LTV refinance pays back your purchase + rehab costs. If you spent $200,000 (purchase + rehab) and the new appraisal is $280,000, a 75% cash-out refinance gives you $210,000—recouping your capital plus a small extra. If the appraisal comes in at $250,000, you can only pull $187,500, leaving $12,500 of your cash trapped in the deal.
Leverage cuts both ways
Leverage amplifies returns on the way up and losses on the way down. A property that drops 20% in value with 75% LTV financing wipes out 80% of your equity. A property that drops 25% puts you underwater—owing more than the property is worth—which forecloses your ability to refinance or sell without bringing cash to closing.
Conservative investors cap leverage at 60–70% LTV, maintain 6+ months of reserves per property, and stress-test deals with 0% appreciation. Aggressive investors push LTVs to 80%, use interest-only loans, and rely on appreciation to bail them out. Both strategies have worked—and both have failed—depending on the cycle.
What I'd actually do
Before buying any rental, run all five metrics. A deal that meets the 1% rule but produces negative cash-on-cash at current rates may still work via appreciation—but you're speculating, not investing. Cap rate, cash-on-cash, and IRR together tell you whether you're being paid for the risk you're taking.
Want to model a specific property? Our Rental Property ROI Calculator handles cap rate, cash-on-cash return, cash flow, and amortization so you can compare deals apples to apples before you commit a dollar.