Fifty Percent Rule
A rough estimate that roughly 50% of gross rental income will be consumed by operating expenses, before debt service.
Definition
The 50% rule is a napkin level shortcut for estimating NOI when you do not have real expense data. You take the gross rent, multiply by 0.5, and the result is your rough estimated NOI. Then you subtract debt service to get cash flow. That is it. It is useful when you are driving around looking at properties and want a sanity check without pulling up a spreadsheet. The rule works because across large samples of single family rentals, operating expenses do tend to average around 45 to 55% of gross rent. But every specific property is different. Low tax states with low insurance and no HOA can run 30 to 40%. High tax states, coastal insurance, and Section 8 compliance costs can push 55 to 65%. The 50% rule is a starting point for back of envelope math, not a substitute for real expense verification. Always verify actual taxes, insurance, and PM fees before making an offer.
Formula
Example
Property grosses $1,800 per month or $21,600 per year. Estimated NOI using the 50% rule = 21,600 x 0.5 = $10,800.
Frequently asked
Does the 50% rule always work?
No. It is an average. Real operating expenses can range from 30% in low cost states to 65% in high tax coastal markets.
Does the 50% rule include debt service?
No. The 50% rule covers operating expenses only. Debt service is subtracted separately to get cash flow.
Is the 50% rule better than the 1% rule?
They answer different questions. 1% rule screens rent to price. 50% rule estimates operating expenses. Use both together.
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