Duplex Rental Calculator
Check whether duplex rental still works after vacancy, operating costs, debt service, and cash invested are all on the page.
Calculator
Duplex Rental Calculator
Add expected rent, reimbursements, lot rent, storage income, parking income, or owner-use savings that belong in the first-pass cash-flow snapshot.
Gross income total: $2,750.00
Use the share of income you expect to lose to vacancy or collection gaps.
Add repairs, taxes, insurance, payroll, utilities, management, CAM, or other non-debt costs that are not already reimbursed.
Operating cost total: $775.00
Add the monthly mortgage or financing payments tied to the property, project, or owner-use space.
Debt service total: $1,170.00
Add reserves for roofs, HVAC, turnovers, appliances, or other larger capital items you want the deal to carry.
Capital reserve total: $0.00
Use the total acquisition price of the property.
Add the down payment, tenant improvements, rehab, closing costs, equipment, or other cash tied up in the property or project.
Cash invested total: $94,000.00
Example values are loaded.
Result
Your result
Duplex Rental produces about $640.00 per month in cash flow on these assumptions.
Monthly cash flow
$640.00
Cap rate
6.48%
Cash-on-cash return
8.17%
Property breakdown
Next steps
Compare before you move on
Most people use one calculator to answer the first question and a related tool to pressure-test the decision.
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Estimate a mortgage payment and see how much principal and interest get paid down during the first year of the loan.
What this calculator shows
A property that looks attractive on top-line income alone can feel very different once vacancy, operating costs, financing, capital reserves, and invested cash are included.
It gives a cleaner first-pass read for comparing rent, expenses, financing, and cash invested before buying a rental before you spend time on a deeper property review.
How to use it
- 1. Add the expected monthly income sources and an allowance for vacancy.
- 2. Add monthly operating costs, capital reserves, debt payments, purchase price, and cash invested.
- 3. Review the resulting reserve-adjusted cash flow, cap rate, and cash-on-cash return.
Formula and assumptions
Effective income equals gross income after vacancy loss.
Monthly cash flow equals effective income minus operating costs, capital reserves, and debt service, while cash-on-cash return uses annual cash flow divided by cash invested.
Notes
This estimate is directional. Use residential rent, expense, reserve, and financing assumptions that fit the property you are reviewing. It is a first-pass rental snapshot, not a lease-by-lease or lender underwriting model.
Worked example
A property can look profitable on paper until vacancy and operating costs are added alongside the mortgage payment.
This example uses the default sample inputs loaded on reset. It does not update with the live calculator entries above.
Monthly cash flow
$640.00
Cap rate
6.48%
Cash-on-cash return
8.17%
Feedback
Found a problem on this page?
Report confusing fields, broken math, or missing assumptions with the exact inputs you used so the issue can be reproduced.
FAQ
FAQ
Why is vacancy included even when the unit is currently occupied?
Because rental income is rarely perfect over a long hold period, and vacancy or collection loss is part of a realistic underwriting buffer.
FAQ
Is cash-on-cash return the same as total return?
No. Cash-on-cash looks only at annual cash flow relative to cash invested and does not include appreciation, loan amortization, or sale proceeds.