Mortgage Overpayment Savings Calculator

How mortgage overpayments save you money

Every time you overpay, that extra amount comes straight off your outstanding balance. Because mortgage interest is charged on the balance you still owe, a smaller balance means less interest builds up the following month — and that saving compounds for every month left on your mortgage.

The effect is largest early in your mortgage term, when the balance — and the interest charged on it — is at its highest. Overpaying consistently from early on can shave years off your mortgage and save thousands in interest, even from relatively modest monthly amounts.

This calculator keeps your monthly payment fixed at your normal payment plus your chosen overpayment, and works out how much sooner you'd clear the mortgage and how much interest you'd avoid paying as a result, compared with sticking to your original term.

Most UK lenders let you overpay up to 10% of your outstanding balance each year without charge, but check your specific mortgage terms first — going over that limit on a fixed-rate deal can trigger an early repayment charge that eats into any savings.

Use the calculator above to see how your own overpayment amount could change your mortgage term and total interest bill.