Mortgage Overpayment Calculator

Should I overpay my mortgage?

Enter your mortgage balance, interest rate, term and a monthly overpayment. The calculator compares your original repayment schedule with an accelerated one and shows the time saved and the interest saved, with a chart of your balance falling to zero sooner.

Why early overpayments help most

• Front-loaded interest: early in a mortgage most of each payment is interest, so overpayments then have the biggest impact.
• Compounding savings: a lower balance means lower interest every month thereafter.
• Guaranteed return: overpaying effectively earns your mortgage rate, risk-free.

Estimates use the standard amortisation formula and assume the overpayment reduces the term. Check your lender's annual overpayment limit and any Early Repayment Charge before overpaying.

Frequently Asked Questions

How do overpayments pay off a mortgage faster?

Any amount above your normal payment comes straight off the balance. A smaller balance accrues less interest each month, so more of every future payment also reduces the capital — a compounding effect that can cut years off the term.

How much interest could I save?

It depends on your rate, balance and how early you start, but on a typical 25-year mortgage even £100–£200 a month extra can save thousands of pounds and shave several years off the term. Enter your figures to see the exact amount.

Are there limits on overpayments?

Many UK lenders let you overpay up to 10% of the outstanding balance each year without penalty. Beyond that, or during some fixed-rate deals, an Early Repayment Charge (ERC) may apply. Check your mortgage terms first — this tool does not include any ERC.

Should I overpay or save the money instead?

Overpaying gives a guaranteed return equal to your mortgage rate. If a savings account or investment reliably earns more after tax, saving may win; otherwise overpaying is a safe, guaranteed benefit. Many people keep an emergency fund first.

Will overpaying lower my monthly payment?

Usually it shortens the term rather than reducing the payment, though some lenders let you choose to lower the monthly amount instead. This calculator assumes the term is shortened, so the benefit shows up as an earlier payoff and less interest.