The cap rate, or capitalization rate, is the unlevered return on a property, conveyed as a percentage of a property's market value. It is used in the income approach to real estate valuation. To calculate a cap rate, you will need a property's net operating income (NOI) and market value. Alternatively, to calculate a property's market value, you will use a cap rate and the property's net operating income (NOI). For more on net operating income, see Calculating Multifamily NOI.