Free rental property calculator estimates IRR, capitalization rate, cash flow, and other financial indicators of a rental or investment property considering tax, insurance, fees, vacancy, and appreciation, among other factors. Also explore hundreds of other calculators addressing real estate, personal finance, math, fitness, health, and many more. How to Calculate the ROI on a Rental Property. The capitalization rate is the rate of return on a real estate investment property based on the income that the property is expected to generate What is the return on my real estate investment? Purchase price, loan terms, appreciation rate, taxes, expenses and other factors must be considered when you evaluate a real estate investment. Use this calculator to help you determine your potential IRR (internal rate of return) on a property.