What is the 50% rule for rental property expenses?
The 50% rule estimates that a rental's operating expenses, everything except the mortgage, will average about half of its gross rent over time. A property renting for $2,000 a month should expect about $1,000 a month in expenses. It is a fast first-pass screen, never a substitute for an itemized expense estimate on a real deal.
The 50% rule says that over time, a rental property's operating expenses will average about 50% of its gross rent. Rent for $2,000/mo, expect about $1,000/mo to go to running the property, before the mortgage. What's left after expenses is your estimated NOI; subtract the loan payment and you have a first-pass cash flow number in your head.
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What's inside the 50%
The rule bundles every cost of operating the property: property taxes, insurance, vacancy, repairs, capital-expenditure reserves (roof, HVAC, water heater), property management, and any owner-paid utilities. It works as a long-run average because the lumpy items (a vacancy month, a $9,000 roof) even out across years, even when any single year looks nothing like 50%.
Where the 50% rule breaks
- High-tax, high-insurance markets run over. In parts of Texas, New Jersey, or coastal Florida, taxes and insurance alone can eat 25 to 35% of rent before a single repair.
- Low-rent properties run over. A furnace costs the same in a $900/mo rental as in a $2,400/mo one. Fixed costs make cheap units run well past 50%, which is exactly where 1%-rule screening tends to point.
- Old housing stock runs over; new builds run under. Age drives repairs and capex more than any average captures.
- "I'll self-manage" doesn't delete the management line. Your time has a cost, and the day you scale or move, the 8 to 10% comes back. Underwrite as if you pay it.
50% is a placeholder for real numbers, not a substitute for them.
From placeholder to real numbers
The 50% rule is for the minute when you have a rent figure and nothing else. Before you offer, replace it: the actual tax bill is public record, an insurance quote takes a phone call, and vacancy rates are knowable by market. BuyBox underwrites with itemized expenses: taxes, insurance, vacancy, repairs, and management as separate lines feeding NOI and DSCR, plus a capital-expenditure reserve held below NOI, beside the mortgage payment, on the way to cash flow. Hover any number to see the formula and inputs behind it. The full walk-through is in How to analyze a rental property.