NOI Calculator

What the NOI calculator does

The NOI calculator works out the net operating income of a rental property: the annual profit from operations before mortgage payments and income tax. Starting from gross rent, it subtracts an allowance for vacancy and credit loss, then operating expenses, leaving the cash the property produces from letting alone.

Net operating income drives valuation through the capitalisation rate, shows whether a property can cover its debt, and lets you compare very different deals on a basis that ignores financing. The calculator makes it quick to screen opportunities and test assumptions.

How net operating income is calculated

Gross rental income is the total rent the property would collect over a year if every unit were let at market rent for the whole period.

No property stays fully occupied, and some rent is never collected. Reducing gross rent by a realistic vacancy and credit loss percentage gives the effective gross income, the rent you can expect to receive.

Subtracting the operating expenses, the recurring costs of running the property, gives net operating income:

NOI = Gross rental income × (1 − vacancy %) − operating expenses

Skipping the vacancy allowance overstates income, and leaving out real expenses flatters the return.

What belongs in operating expenses

Most NOI estimates go wrong on the expense figure. Operating expenses include:

• Property management fees, whether paid to an agent or valued as your own time.
• Insurance on the building and liability cover.
• Property taxes or local rates levied on the owner.
• Repairs and maintenance, from routine upkeep to periodic fixes.
• Utilities the owner pays instead of the tenant.
• Reserves set aside for larger future repairs.

Mortgage principal and interest are excluded, because financing is specific to each buyer. Income tax is excluded because it depends on personal circumstances. Depreciation is a tax concept, not a cash cost, and one-off capital improvements such as a new roof are treated as capital spending. Keeping these items out is what makes NOI comparable across properties.

Why NOI excludes financing

Two investors might buy the identical building, one paying cash and the other borrowing most of the price. Their profits after debt would look completely different, yet the building earns the same from its tenants, and NOI measures that shared earning power.

You can judge the asset on its own and then add your funding afterwards. Subtracting annual debt service from NOI gives the cash flow before tax, and dividing NOI by debt service gives the debt service coverage ratio that lenders check.

Using NOI to value a property

Dividing NOI by the purchase price gives the cap rate, an annual yield that lets you compare properties and markets. Dividing NOI by the cap rate that similar assets trade at gives an implied price.

Because value is NOI divided by a small percentage, a modest change in NOI can move the valuation substantially. Raising rents, cutting a recurring cost, or reducing vacancy all lift NOI, and at a typical cap rate each extra unit of NOI can add many times its own size to the property's worth. Value-add investing relies on this: improve the operating income and the capital value follows.

How to use the calculator

1. Enter the gross rental income, the full annual rent at full occupancy.
2. Enter a vacancy and credit loss percentage that reflects the local market and the property's history.
3. Enter the annual operating expenses, excluding the mortgage.

The tool returns the effective gross income and the net operating income, and the chart shows how the gross rent splits between the NOI you keep and the portion lost to vacancy and expenses.

Keeping the estimate realistic

• Base gross income on achievable market rent, not the most optimistic asking figure.
• Do not assume zero vacancy. Even strong markets see turnover.
• Include every recurring cost. Forgotten expenses are the most common reason a deal looks better on paper than in practice.
• Keep large, occasional replacements separate from routine operating costs.

The result shows whether a property earns enough to justify its price, whether the rent can carry the likely debt, and how much room there is to add value by improving operations.

This article is general information only and is not financial advice.

About This NOI Calculator

Use this NOI calculator to get an instant estimate based on the figures you enter. Adjust the inputs above to match your situation, or browse all our calculators to plan your next step.