How to Analyze a Rental Property
Before buying a rental property, smart investors evaluate it across four key metrics: cap rate, cash-on-cash return, gross rent multiplier (GRM), and monthly cash flow. Using all four together gives you a complete picture of whether a property is likely to be profitable — and how quickly you'll recover your initial investment.
Key Metrics Explained
Cap Rate (Capitalization Rate)
Cap rate measures a property's income potential independent of financing. It's the ratio of Net Operating Income to purchase price — useful for comparing properties regardless of how they're financed.
| Cap Rate | Market Type | Interpretation |
|---|---|---|
| 8%+ | Secondary / rural | High return, higher risk |
| 5–8% | Suburban | Solid rental investment |
| 4–6% | Major metros | Normal for high-appreciation markets |
| <4% | Gateway cities (NYC, SF, LA) | Appreciation play, not cash flow |
Cash-on-Cash Return
Cash-on-cash return measures the actual cash yield on your out-of-pocket investment — it accounts for mortgage payments, making it the most practical metric for leveraged investors.
A cash-on-cash return of 6–10% is generally considered good for a rental property. Anything above 10% is excellent; below 4% is often better than a savings account but may not justify the risk and effort.
Gross Rent Multiplier (GRM)
GRM is a quick-filter metric: divide the purchase price by annual gross rent. Lower is generally better. A GRM under 10 is often considered favorable; above 15 means the price is high relative to rental income.
Net Operating Income (NOI)
NOI is gross income minus all operating expenses — but before mortgage payments. It's used to calculate cap rate and is a key number for lenders. NOI does not include mortgage P&I, income taxes, or depreciation.
The 1% Rule
The 1% rule is a quick screening tool: a rental property should generate monthly rent equal to at least 1% of its purchase price. A $200,000 property should rent for $2,000/month. It's a rough filter, not a guarantee of profitability — use the full analysis above to confirm.
In high-cost markets (coastal cities), hitting 1% is often impossible. In those markets, investors rely more on appreciation than cash flow. In the Midwest and South, many properties easily clear 1%.
The 50% Rule
The 50% rule estimates that operating expenses (excluding mortgage) will consume about 50% of gross rental income over time. It's a conservative shortcut for back-of-napkin analysis. This rule often holds for older properties but may overstate expenses for newer builds with lower maintenance costs.
Vacancy Rate — What to Assume
Most experienced landlords use a 5–10% vacancy rate in their projections. This accounts for time between tenants, evictions, and unexpected vacancies. In strong rental markets with low supply, you might run at 2–3%. In weak markets or with a difficult property type, budget 10–15%.
Property Management
If you're self-managing, your "cost" is time, not money. Professional property managers typically charge 8–12% of monthly rent plus leasing fees (often one month's rent per new tenant). Factor this in even if you plan to self-manage — it reflects the true economic cost and protects your projections if you ever need to hire help.
Should You Buy This Property?
There's no single number that makes a rental property a good or bad investment — it depends on your goals. Cash flow investors want positive monthly cash flow and 6%+ cash-on-cash. Appreciation investors may accept negative cash flow in markets with strong price growth. BRRRR investors care most about post-rehab ARV and refinance potential.
- Cash flow positive — property pays for itself and generates income from day one
- Break-even — tenant covers all expenses, equity builds over time
- Negative cash flow — only viable in high-appreciation markets with a clear exit strategy
Common Mistakes in Rental Property Analysis
- Forgetting capital expenditures (roof, HVAC, appliances) — budget 5–10% of rent/year
- Using optimistic rent estimates instead of current market data
- Ignoring vacancy — even great properties have turnover
- Underestimating closing costs and rehab
- Not accounting for rising property taxes after purchase
- Confusing NOI with cash flow (NOI doesn't include mortgage)
This calculator is for educational and planning purposes only. It does not constitute financial, tax, or investment advice. Consult a licensed real estate professional, CPA, or financial advisor before making investment decisions.