Mortgage Overpayment Calculator

Our mortgage overpayment calculator shows how much interest you save by making extra repayments. Even £100/month extra on a £200,000 mortgage saves around £15,000 in interest and nearly 3 years. Most lenders allow up to 10% overpayment per year without charges.

Enter outstanding balance, current interest rate, and remaining term. Then add a monthly overpayment amount. Overpayments reduce the outstanding capital, which reduces the interest charged in every subsequent month — the benefit compounds. Early overpayments save more than later ones because the saving applies over a longer remaining term. Check your mortgage terms before overpaying: most fixed-rate deals allow up to 10% of the outstanding balance per year without early repayment charges. On a variable or tracker mortgage, there is typically no restriction. The calculator shows total interest saved and term reduction from the overpayment — for most borrowers, the combination of these two figures makes the case for overpayment compelling.