How to Analyze a Rental Property: Cap Rate, Cash-on-Cash Return and NOI Explained

Two properties with the same price can be very different investments. One might produce steady income for decades; the other might quietly lose money every month. The difference is rarely obvious from the listing photos. It shows up in the numbers. This guide explains the key metrics investors use and walks through a full example.

Start with realistic income

Begin with gross scheduled rent: the rent the property would earn if every unit were leased all year at market rates. Confirm market rent by looking at comparable rental listings nearby — same size, same condition, same neighborhood — rather than relying on the seller's estimate.

Then subtract an allowance for vacancy and credit loss. Even great properties sit empty between tenants. Many investors use 5–8% of gross rent for long-term rentals and more for furnished or seasonal rentals. Add any other income, such as parking or laundry, to get effective gross income.

List every operating expense

Operating expenses are the costs of running the property, excluding the mortgage. Typical items include:

• Property taxes and insurance.
• Property management (often 8–10% of collected rent for single-family homes).
• Repairs and maintenance.
• Capital expenditure reserves for roofs, HVAC, water heaters and appliances.
• Utilities paid by the owner, landscaping, snow removal and pest control.
• Homeowners' or condominium association fees.
• Leasing costs, accounting and legal fees.

Include management even if you plan to self-manage. Your time has value, and you may want to hire a manager later.

Net operating income (NOI)

NOI = effective gross income − operating expenses. NOI tells you how much the property itself produces before financing. It is the foundation for nearly every other metric and for how lenders and appraisers value income property.

Cap rate

Cap rate = NOI ÷ purchase price. A property earning $24,000 of NOI and priced at $400,000 has a 6% cap rate. Cap rates let you compare properties without the noise of different loans. Lower cap rates usually signal lower perceived risk or stronger growth expectations; higher cap rates often signal higher risk, weaker locations or more management intensity.

Cap rates are a snapshot. A low cap rate is not automatically bad if you expect strong rent growth, and a high cap rate is not automatically good if the building needs major repairs.

Cash flow and debt service

Cash flow = NOI − annual debt service (principal and interest). Interest rates have a large influence here; use our mortgage calculator to estimate payments at different rates and down payments.

Lenders also look at the debt service coverage ratio (DSCR): NOI divided by debt service. Many investment loans require a DSCR of at least 1.2–1.25.

Cash-on-cash return

Cash-on-cash return = annual pre-tax cash flow ÷ total cash invested. Total cash invested includes the down payment, closing costs and any upfront repairs. This metric answers a simple question: what am I earning on the money I actually put in?

A worked example

Imagine a three-bedroom single-family home priced at $350,000 that should rent for $2,600 per month.

• Gross scheduled rent: $2,600 × 12 = $31,200
• Vacancy at 6%: −$1,872 → effective gross income $29,328
• Property taxes $5,600, insurance $2,100, management at 9% $2,640, maintenance $1,800, capital reserves $1,800, other $600 → operating expenses $14,540
• NOI = $29,328 − $14,540 = $14,788
• Cap rate = $14,788 ÷ $350,000 = 4.2%

Now add financing: 25% down ($87,500) and a $262,500 loan at 6.75% over 30 years, roughly $1,703 per month or $20,436 per year. Cash flow is $14,788 − $20,436 = −$5,648 per year.

That property loses money on these assumptions. To make it work, the investor would need a lower price, more rent, a larger down payment or a belief that appreciation and loan paydown will outweigh the negative cash flow — a much riskier bet.

Quick screening rules (and their limits)

The 1% rule says monthly rent should be at least 1% of the price. Our example ($2,600 on $350,000) is 0.74%, which flagged the problem early. The 50% rule estimates that operating expenses will be about half of rent. These shortcuts help you sort dozens of listings quickly, but they are not a substitute for a full analysis — taxes, insurance and association fees vary enormously between markets.

Look beyond the first year

• Rent growth and expense growth: insurance and taxes have risen faster than rents in some regions.
• Loan paydown: part of each payment builds equity even when cash flow is thin.
• Exit assumptions: what might the property sell for, and what will selling cost?
• Taxes: depreciation can shelter rental income; speak to an accountant about your situation.

Checklist before you make an offer

1. Verify market rent with at least three comparable rentals.
2. Get actual tax bills and an insurance quote, not estimates.
3. Budget for vacancy, management and capital expenditures.
4. Run cash flow at today's interest rate and at a rate one point higher.
5. Calculate cash-on-cash return including all upfront costs.
6. Decide in advance the maximum price at which the deal still works.

Disciplined analysis will not make every investment a winner, but it will keep you out of most of the bad ones. When you are ready, compare live properties for sale using these numbers.

Figures are illustrative only and do not represent any specific listing. This article is not financial advice.