The prepayment penalty is an agreement made between a borrower and a mortgage lender which regulates the time period of the borrower to allow for pay off, associated with a mortgage or with a promotion.An online mortgage/loan prepayment penalty calculator useful for you to estimate the total mortgage payoff and prepayment penalty. Enter loan amount and interest in the below prepayment penalty mortgage calculator to know Mortgage pre-payment penalty and Total Mortgage Payoff.