50% Rule (Rental) Calculator
The 50% rule is a quick way to estimate how much of a rental property's rent survives after the bills are paid. The idea is that, averaged over years, roughly half of gross rent goes to operating costs: property taxes, insurance, repairs and maintenance, property management, and an allowance for vacancy. Whatever is left is a rough net operating income before the mortgage. The math could not be simpler. Take the gross monthly rent, multiply by 0.50 to estimate operating expenses, then subtract that from the rent to estimate net operating income. For 1,800 dollars of rent, that means about 900 dollars of expenses and about 900 dollars of net operating income each month. This calculator takes one input, the monthly rent, and returns both figures so you can sense whether a property has room to cover financing and still produce cash flow. It is a screening estimate, not a budget: it ignores the expense mix and excludes the loan payment, which you subtract separately. Use it to compare deals fast, then build a line by line expense schedule before you commit. Every figure here is computed deterministically from the formula shown below, with a worked example that reconciles exactly to the calculator so you can follow each step.
The 50% rule estimates operating expenses as half of gross rent and treats the rest as net operating income: expenses = rent x 0.50 and NOI = rent - expenses. A monthly rent of $1,800 implies estimated expenses of $900.00 and estimated net operating income of $900.00 a month before any mortgage payment.
50% rule formula
Estimated operating expenses = Monthly rent x 0.50
Estimated net operating income = Monthly rent - Operating expenses
Net operating income is before any mortgage payment
Subtract principal and interest separately for cash flow
The rule splits gross rent in half. One half is assumed to cover operating costs; the other half is the net operating income that remains to service debt and, ideally, leave a profit.
Worked example
A rental collects 1,800 dollars in gross rent each month. Apply the 50% rule to estimate the operating expenses and the net operating income.
- Estimated operating expenses = 0.50 x 1,800 = 900
- Estimated net operating income = 1,800 - 900 = 900
- About 900 dollars a month remains before any mortgage payment
Estimated expenses are 900 dollars and estimated net operating income is 900 dollars. This is the calculator's default input, so the result above matches the widget exactly.
How the split works
| Component | Share of gross rent | What it covers |
|---|---|---|
| Operating expenses | 50% | Taxes, insurance, repairs, management, vacancy |
| Net operating income | 50% | Available before the mortgage payment |
| Mortgage payment | Varies | Subtracted from NOI to find cash flow |
The 50 percent split is a general rule of thumb, not official guidance. Actual expense ratios vary by property and location.
50% rule calculator: frequently asked questions
What is the 50% rule in real estate?
The 50% rule is a shortcut for estimating a rental property's operating expenses. It assumes that, over time, roughly half of the gross rent will be consumed by costs such as taxes, insurance, repairs, management and vacancy. Whatever is left is a rough net operating income before any mortgage payment.
How do I use the 50% rule?
Take the gross monthly rent and multiply it by 0.50 to estimate operating expenses. Subtract that from the rent to estimate net operating income. For 1,800 dollars of rent, expenses are about 900 dollars and net operating income is about 900 dollars a month before debt service.
Does the 50% rule include the mortgage payment?
No. The 50 percent figure covers operating expenses only, not the loan payment. After you estimate net operating income with this rule, subtract your principal and interest payment separately to get a rough cash flow before taxes.
Is the 50% rule accurate?
It is a screening estimate, not a precise figure. Actual expense ratios vary with property age, location, taxes and management. Newer or self managed properties may run lower; older or heavily taxed properties may run higher. Use the rule to shortlist deals, then build a line by line budget.
When should I not rely on the 50% rule?
Avoid leaning on it for properties with unusual cost structures, such as those with very high property taxes, extensive deferred maintenance, or tenant paid utilities. In those cases the 50 percent assumption can be well off, so verify each expense from real records before committing.
Official sources
- Buying a house, renting and mortgage basics: US Consumer Financial Protection Bureau (CFPB). As at 25 June 2026.
Reviewed by the CalculatorHub team, edited by James Graham, 25 June 2026. See our methodology. This is general information, not financial, tax, legal or investment advice.