The Federal Reserve Board mortgage calculator is designed to help you compare the monthly payments and the amount of equity you will build in your home for several kinds of fixed and adjustable-rate mortgages. You can get more information on how to use this calculator and learn important information about the calculations you will see. Select the types of mortgages you want to compare by filling in interest rates for those mortgages. You can find information about interest rates on the Internet, in newspapers, or from your financial institution, lender, or broker. You will need to compare at least one fixed-rate mortgage with at least one adjustable-rate mortgage.

https://www.federalreserve.gov/apps/mortcalc/