Crunch Free Rental Property Analyzer
Underwrite any rental deal in under a minute: monthly cash flow, net operating income, cap rate, and cash-on-cash return — all from one screen.
Purchase & financing
Income
Monthly expenses
| Effective monthly rent (after vacancy) | $0 |
| Mortgage payment (P&I) | $0 |
| Total monthly expenses | $0 |
| Annual net operating income (NOI) | $0 |
| Cap rate | 0% |
| Cash-on-cash return | 0% |
| Total cash invested (down + 3% closing) | $0 |
| Loan amount | $0 |
How it works
The mortgage payment uses standard amortization: M = P × r(1+r)n / ((1+r)n − 1). Effective rent = rent × (1 − vacancy). Operating expenses (tax, insurance, HOA, maintenance, management, other) exclude the mortgage. NOI = (effective rent − operating expenses) × 12. Cap rate = NOI ÷ purchase price. Cash-on-cash = annual cash flow ÷ total cash invested (down payment + ~3% closing costs).
Formula & worked example
Formula: Effective rent = rent × (1 − vacancy %). The mortgage P&I payment uses the standard loan formula on price − down payment. NOI = (effective rent − monthly operating expenses) × 12 and cap rate = NOI ÷ price. Monthly cash flow = effective rent − P&I − operating expenses, and cash-on-cash = annual cash flow ÷ cash invested, where cash invested = down payment + 3% of the price for closing costs.
Worked example: A $200,000 rental with 20% down and a 6.5%, 30-year loan: P&I is $1,011 a month on $160,000. Rent of $1,800 at 5% vacancy gives $1,710 of effective rent; $524 a month of expenses leaves $14,232 a year of NOI (a 7.1% cap rate) and $175 a month of cash flow — a 4.6% cash-on-cash return on the $46,000 invested.
Frequently asked questions
What makes a rental property a good deal?
Positive monthly cash flow after ALL expenses (including vacancy and maintenance reserves), in a market with stable or growing rents. Many investors target at least $200–$300/month cash flow per door on single-family rentals.
What is the 1% rule?
Monthly rent should be at least 1% of the purchase price (a $300,000 home renting for $3,000/mo). It's a quick screening filter, not a valuation — in expensive markets few deals pass it, so use the full analyzer above for real numbers.
Cap rate vs cash-on-cash — what's the difference?
Cap rate measures the property's unleveraged return (NOI ÷ price), so it's perfect for comparing properties regardless of financing. Cash-on-cash measures return on YOUR cash invested, so it reflects your leverage — the same property shows higher CoC with a smaller down payment.