A fast screening rule real estate investors use before running detailed numbers — roughly half of gross rent typically goes to operating expenses, before the mortgage payment.
How it works
Half of monthly rent is treated as estimated operating expenses (taxes, insurance, maintenance, vacancy, and management, but not the mortgage). The other half is the estimated net operating income; subtracting the mortgage payment from that gives estimated monthly cash flow.
What this does not include
This is a rough screening estimate, not a substitute for a detailed expense analysis — actual operating expenses can run well above or below 50% of rent depending on the property’s age, location, and management structure.
How to use this calculator
- Enter monthly rent and, optionally, the monthly mortgage payment.
A worked example
$2,000 monthly rent, no mortgage payment: estimated expenses (50% rule) = $1,000, estimated NOI = $1,000, estimated cash flow = $1,000.
The same rent with a $600 mortgage payment: estimated cash flow = $400 — after estimated operating expenses and the actual mortgage payment.
What the variables mean
| Variable | Meaning |
|---|---|
| Monthly rent | Expected gross monthly rental income |
| Mortgage payment | Monthly mortgage payment, if financed |
Edge cases worth knowing
The 50% rule is a rough screening tool, not an exact expense calculation. It assumes roughly half of rental income goes to operating expenses (taxes, insurance, maintenance, vacancy) — actual expenses vary by property age, location, and management style.
Zero monthly rent makes the calculation meaningless, so the calculator declines to show a result for that input.
Frequently asked questions
Is the 50% rule always accurate?
No — it’s a rough rule of thumb meant for quick screening, not a precise expense projection; older properties, self-managed units, or unusually low-tax areas can all shift actual expenses well away from 50%.
How is this different from the 1% rule?
The 1% rule checks whether rent is high enough relative to purchase price; the 50% rule instead estimates operating expenses as a share of that rent — they answer different screening questions.
What counts as an operating expense here?
Property taxes, insurance, maintenance, vacancy losses, and property management — everything involved in running the property except the mortgage payment itself.
