You can calculate net operating income (NOI) for your real estate investment by using the generally accepted net operating income formula, which is your potential rental income plus any additional property-related income minus vacancy losses minus total operating expenses.
Keep in mind the net operating income formula can vary depending on who calculates it.
For example, most investors separate potential rental income and other income, but sometimes you will see them combined. Regardless, the generally accepted net operating income formula is your potential rental income plus any additional property-related income minus vacancy losses minus total operating expenses.