Less-Than-20% Down Calculator (14b) PMI (Mortgage Insurance) Versus Higher Interest Rate Versus Piggyback Who This Calculator is For: Borrowers who cannot put 20% down, selecting between borrower-pay mortgage insurance, lender-pay mortgage insurance where the borrower pays a higher interest rate on the first mortgage, and a piggyback consisting of an 80% first mortgage plus a higher-rate second mortgage What This Calculator Does:This calculator compares the total cost of each of the three options above.