Rental Cash Flow Calculator
Underwrite a rental property: monthly cash flow, cap rate, cash-on-cash return, and the 1% rule.
Your details
Income
Parking, storage, laundry, pet rent
Operating expenses
This calculator runs entirely on your device. Nothing you enter is uploaded, stored, or sold. How this works
Monthly shortfall
-$190.33
-$2,284 per year
Includes your inputs, the full breakdown, and every row of the table.
Cap rate
5.27%
NOI $16,877 / price
Cash-on-cash return
-2.46%
$93,000 invested
1% rule
0.81%
Below the 1% guideline
DSCR
0.88
Lenders usually want 1.20+
- Gross scheduled income
- $2,600.00
- Vacancy (5.0%)
- - $130.00
- Effective gross income
- $2,470.00
- Property tax
- - $316.67
- Insurance
- - $133.33
- Maintenance
- - $208.00
- CapEx reserve
- - $208.00
- Management
- - $197.60
- Net operating income
- $1,406.40
- Debt service
- - $1,596.73
- Cash flow
- -$190.33
What this means
- Maintenance and CapEx reserves are not optional. A roof, HVAC, or water heater will eventually arrive, and averaging their cost into every month is what separates a real pro forma from wishful thinking.
- This property is negative on a full-reserve basis. That can still work for appreciation plays, but it means writing a check every month.
How the rental cash flow calculation works
A rental pro forma has two layers. Net operating income (rent, minus vacancy, minus every operating expense) describes the property itself and drives the cap rate. Subtract debt service and you get cash flow, which describes your deal — the same house financed two different ways produces two very different returns.
The most common way new investors overstate returns is by omitting reserves. Rent minus mortgage, taxes, and insurance looks great until the first turnover, the first vacancy, and the first $9,000 HVAC replacement. Budgeting 8% for maintenance and 8% for capital expenditures is conservative but survivable.
Frequently asked questions
What is a good cap rate?
It depends entirely on the market. Expensive coastal metros trade at 3-5% caps; Midwest and Southeast markets often run 6-9%. Compare a property to other listings in the same submarket, not to a national number.
Is the 1% rule still useful?
As a screening filter, yes. As a buying criterion in high-price markets, it has been unreachable for years. Use it to sort a list quickly, then underwrite the survivors with the full cash flow model.
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Disclaimer. This calculator is provided for general information and educational purposes only and does not constitute financial, tax, legal, medical, or engineering advice. Results are estimates based on the inputs you provide and the assumptions described above. Confirm any figure with a qualified professional before acting on it.