12 Real Estate Investing Calculations You Need to Know Net Operating Income (NOI) NOI = Operating Income – Operating Expenses Net Operating Income (NOI) is the income left after accounting for your operating expenses and BEFORE debt service. Net operating income is one of the most important numbers you should know, because it’s also used in so many other calculations (such as cap rate, debt coverage ratio, etc.) NOI take into account your gross income, vacancy loss, and operating expenses such as maintenance, repairs, taxes, insurance, and property management. Basically all expenses except for the principal and interest on your mortgage payment and capital expenses. NOI is what you have left at the end of the day to pay your lender – and therefore your lender finds this number extremely interesting. Net Operating Income Example: Let’s say you have a property that rents for $1,500 per month and we assume…