Underwrite
Cash flow positive rental calculator
Cash-flow positive means money left after the operating stack and the loan - not "rent covers the PITI on a good month." Enter rent, vacancy, OpEx, and debt service; see monthly/annual cash flow and a clear positive / breakeven / negative badge against a cushion you set (e.g. ≥ $0 or ≥ $200/mo).
Assumptions
Returns stack
- NOI (annual)
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- Monthly cash flow
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- Annual cash flow
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- Badge
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When to use
Binary gut-check before you fall for the kitchen; stress-testing vacancy; explaining "positive" to a partner who ignores repairs.
When not to
Principal paydown is equity, usually not "cash flow" here. And $1 positive is a weak pass - set a real cushion.
Assumptions: EGI = gross rent − vacancy (+ other income). NOI = EGI − OpEx. Cash flow = NOI − debt service. Pass if cash flow ≥ your minimum (default $0). CapEx reserve not automatic.
Worked examples
Input
Full stack CF +$275/mo
Output
Positive
Clears a zero cushion - ask whether $275 is enough for your market.
Input
Rent > PI alone CF −$40/mo
Output
Negative
Rent beating PI alone is not positive when taxes, insurance, vacancy, and repairs eat the rest.
Common traps
- Principal paydown is equity, usually not "cash flow" here.
- $1 positive is a weak pass - set a real cushion.
- STR seasonality can flip the badge by month.