Rental Property Cash Flow Calculator (Monthly, With Vacancy and Reserves)
Cash flow is what's left in your account each month after the mortgage payment and running costs. It is not the same as the profit or loss on your tax return, which ignores principal but subtracts depreciation. This calculator handles the cash side; the IRS example below shows the tax side.
Calculator
- Effective rent after vacancy
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- Operating costs and reserves
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- Net operating income
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- Cash flow per year
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- Break-even rent
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Default inputs are an illustration, not market data.
What each input means
- Vacancy %: share of the year you expect the unit to be empty or rent to go uncollected. One empty month a year is about 8.3%.
- Maintenance and capital reserve %: money set aside from each month's rent for repairs and for big-ticket replacements (roof, water heater). These are your own assumptions; there is no official rate.
- Mortgage payment: principal and interest. If taxes and insurance are escrowed, put them in their own fields and leave them out of this one.
- Break-even rent: the monthly rent at which cash flow is exactly zero with your other inputs.
Cash flow vs taxable rental income: the IRS example
Pub. 527 includes a full example: a house rented all 12 months at $1,125 ($13,500 a year) with mortgage interest of $8,000, fire insurance $250, repairs $400, real estate taxes $500 and maintenance $200, which is $9,350 of expenses. Depreciation on the $120,000 building is $4,363. Result on Schedule E: a net rental loss of ($213).
In cash terms the same year leaves $4,150 before any principal payments, because depreciation isn't a cash cost. Principal payments, in turn, cost cash but aren't deductible. Track both views: cash flow tells you whether the property pays its way month to month; Schedule E tells you what you report.
Reading the result
If cash flow is negative, the break-even figure shows how far rent would need to move. Re-run with a higher vacancy % to see how sensitive the property is to one bad month. Nothing here is investment advice; it is arithmetic on your own numbers.
Keep landlord books in these categories
Our rental spreadsheets use Schedule E-style expense categories (you can rename them), track security deposits separately from income, and total everything per property: