Determining which mortgage term is right for you can be a challenge. With a 15 year mortgage you will pay significantly less interest, but only if you can afford the higher monthly payment. Use this calculator to compare these two mortgage terms, and let us help you decide which term is better for you. "> This Financial Calculator requires a Browser with Java Support Definitions Mortgage amount Original or expected balance for your mortgage. Interest rate Annual interest rate for your mortgage. Interest rates are generally lower for shorter term mortgages. Marginal tax rate This is your combined state and federal tax rate. This is used to calculate your potential income tax savings by deducting your mortgage interest. Monthly payment Monthly principal and interest payment (PI). Both 30 year and 15 year mortgages are shown. Total payments Total of all monthly payments over the full term of the mortgage. Both 30 year and 15 year mortgages are shown. Total interest Total of all interest paid over the full term of the mortgage. Both 30 year and 15 year mortgages are shown.