Free calculator

Mortgage overpayment calculator

A monthly overpayment is a guaranteed, tax-free return at your mortgage rate. See exactly what yours would save, and when the mortgage dies.

Mortgage balance£180,000

Interest rate4.5%

Years remaining25

Overpayment per month£200/mo

Most UK lenders allow 10% of the balance per year penalty-free; check your deal's terms before large overpayments.

Interest saved

£35,177

Time shaved

6y 7m

Monthly payment

£1,000

Mortgage-free in

18y 5m

With overpayments Withoutyears

The honest comparison: overpaying earns you your mortgage rate, guaranteed and tax-free. Investing the same money might earn more over decades, with no guarantee and some stomach required. At higher mortgage rates the guaranteed return gets hard to beat; at very low fixed rates the case for investing instead strengthens. Many people sensibly do half and half, and nobody ever regretted owning their home outright.

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Educational information, not financial advice. Figures current as of July 2026 where dated; allowances and rates change, so check the source before acting.