FinanceQA releases a mortgage calculator for Windows to help you calculate your monthly mortgage payments easily. Just enter in your Principal, Annual Interest Rate, and Number Of Monthly payments and click Calculate. You will then be showns what your monthly mortgage will be. FinanceQA created this mortgage calculator to help you learn more about how a mortgage works. Always seek the help of the loan originator to find out what your exact monthly mortgage payment will be. We hope this calculator is easy to use to help you learn more about mortgage payments.