Rental Property Calculator

How to Analyze a Rental Property

Buying a rental property is a business decision first and a real estate transaction second. The purchase price, location, and condition all matter — but none of them tell you whether the property will generate income. That requires a proper financial analysis using four core metrics: cash flow, cash-on-cash return, cap rate, and gross rent multiplier.

This calculator runs all four calculations simultaneously so you can evaluate any property in under two minutes.

Cash-on-Cash Return: Your Real Yield

Cash-on-cash return is the most practical metric for leveraged real estate investors. It measures how much annual cash flow you receive relative to the actual cash you put in — not the full purchase price, but only your out-of-pocket investment.

Formula: Cash-on-Cash Return = (Annual Cash Flow / Total Cash Invested) × 100

Total cash invested includes your down payment plus estimated closing costs (typically 2% of purchase price). Annual cash flow is effective gross rent minus all operating expenses and mortgage payments, multiplied by 12.

Most experienced investors target 6–10% cash-on-cash return as a baseline. Returns above 10% are considered strong. Returns below 4–5% may indicate the property is overpriced relative to its income potential — or that your financing terms are unfavorable.

Note that cash-on-cash return is a pre-tax metric. Actual after-tax returns will differ depending on your depreciation deductions, interest deductions, and tax bracket.

Cap Rate: Evaluating the Property Independent of Financing

Cap rate (capitalization rate) removes financing from the equation entirely. It compares the property's net operating income to its purchase price — letting you evaluate and compare properties regardless of how they're financed.

Formula: Cap Rate = (NOI / Purchase Price) × 100

Net Operating Income (NOI) equals effective gross income minus all operating expenses: property tax, insurance, maintenance, and management fees. Mortgage payments are excluded from NOI because financing varies by buyer.

Typical cap rates range from 4–10% depending on property type, location, and market conditions. Class A properties in prime urban markets often trade at 4–5% cap rates. Class B and C properties in secondary markets commonly trade at 6–9% cap rates. Higher cap rates indicate more income relative to price — but often reflect higher risk, older properties, or weaker rental markets.

Cap rate is most useful when comparing similar properties in the same market. A 7% cap rate is attractive in one city and mediocre in another.

Gross Rent Multiplier: A Quick Screening Tool

GRM is the simplest metric: purchase price divided by annual gross rent. A $300,000 property renting for $2,000/month ($24,000/year) has a GRM of 12.5.

Formula: GRM = Purchase Price / (Monthly Rent × 12)

Lower GRM means more rent per dollar of purchase price. GRM works best as a screening tool when comparing multiple properties quickly — before running a full cash flow analysis. Because it ignores operating expenses and vacancy, it cannot tell you whether a property is profitable, only whether it's relatively inexpensive on a rent-to-price basis.

In most U.S. markets, residential rentals trade at GRMs between 8 and 20. Properties at GRM 8–12 generally have a better chance of meeting the 1% rule. Properties at GRM 18–20 typically generate negative cash flow unless paid in cash.

The 1% Rule: A Starting Screen

The 1% rule is a quick screening heuristic: monthly rent should equal at least 1% of the purchase price. A $250,000 property should rent for at least $2,500/month. Properties meeting this threshold often generate positive cash flow.

The 1% rule is useful for quickly eliminating properties that almost certainly won't cash flow — but passing the 1% screen does not guarantee profitability. Operating expenses, vacancy rates, and financing terms all affect the actual outcome. Always run a full cash flow analysis before making an offer.

In high-cost coastal markets (San Francisco, New York, Los Angeles), the 1% rule is nearly impossible to meet. Investors in these markets rely more heavily on appreciation than current cash flow. In secondary and tertiary markets (the Midwest, Southeast, parts of Texas), the 1% rule is achievable — and some properties exceed it significantly.

Understanding the Expense Ratio

Inexperienced investors consistently underestimate operating expenses. A common rule of thumb is that operating expenses (excluding mortgage) run 35–50% of gross rental income. Higher-expense markets, older properties, and self-managed properties without professional management may run higher.

The main expense categories to estimate carefully:

• Property tax: Varies dramatically by location — from under 0.5% in some states to over 2.5% in others. Check the actual tax bill for the property, not just the county average.
• Insurance: Landlord insurance (not homeowner's insurance) typically runs $800–$2,000/year for a single-family home, more for multi-family or in high-risk areas.
• Maintenance: Budget 1–2% of property value per year for routine maintenance and repairs. Older properties, multi-family units, and properties with more systems (pools, HVAC, etc.) trend toward 2%+.
• Property management: Professional management typically costs 8–12% of collected rent. Even if self-managing, consider what your time is worth.
• Vacancy: No property is rented 12 months a year every year. Budget 5–10% vacancy as a standard assumption. Higher turnover markets or properties may warrant 10–15%.

A Worked Example

You find a single-family rental priced at $300,000. Comparable rents in the area are $2,200/month. You plan to put 25% down ($75,000) at a 7.5% mortgage rate on a 30-year loan. Local property taxes are $3,600/year, insurance is $1,200/year, you estimate 1% maintenance ($3,000/year), and vacancy at 5%.

• Loan amount: $225,000
• Monthly mortgage: approximately $1,573
• Effective monthly rent: $2,200 × 95% = $2,090
• Monthly expenses: $1,573 + $300 + $100 + $250 = $2,223
• Monthly cash flow: $2,090 − $2,223 = −$133 (slightly negative)
• Total cash invested: $75,000 + $6,000 (closing) = $81,000
• NOI: $26,400 gross − 5% vacancy − $7,800 operating expenses = $17,220
• Cap rate: $17,220 / $300,000 = 5.74%
• GRM: $300,000 / $26,400 = 11.4

This property generates a slightly negative cash flow at current rates — but the cap rate of 5.74% is reasonable, and with 20% down instead of 25%, the loan would be smaller and cash flow closer to breakeven. Small changes in rent, vacancy assumptions, or down payment materially affect the outcome, which is exactly why running multiple scenarios is valuable.

Questions You Might Ask