See how overpaying reduces your mortgage term
Mortgage Overpayment Calculator
Find out how much interest you save and how much sooner you'll be mortgage-free by making regular or one-off overpayments on your UK mortgage.
Enter your details
Added to your regular payment each month
Applied once per year
Total interest saved
£41,667
Paid off 5 yr 4 mo sooner by paying an extra £200/month
Old payoff
25 years
£174,176 total interest
New payoff
19 yr 8 mo
£132,508 total interest
Time saved
5 yr 4 mo
Interest saved
£41,667
Monthly payment comparison
Current monthly payment
£1,388
New monthly payment
£1,588
How this calculator works
Most UK lenders allow you to overpay by up to 10% of your outstanding balance per year without incurring Early Repayment Charges (ERCs). Within this limit, overpayments are a powerful way to reduce your total interest bill.
Because mortgage interest in the UK is calculated daily on your outstanding balance, reducing your balance faster through overpayments has an immediate impact on the interest you're charged each month.
Even modest overpayments add up significantly over a 25-year term. If you're on a fixed rate, check with your lender before overpaying above the 10% threshold, as ERCs can be substantial.
Worked example
- 1Standard monthly repayment: £1,388
- 2New effective payment: £1,688/month
- 3Standard total interest: £174,150
- 4With £300 overpayment: £114,200
- 5Interest saved: ~£59,950 | Time saved: ~7 years
Frequently Asked Questions
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Try calculatorDisclaimer: Calculations are estimates for general guidance only and do not constitute regulated financial advice. Rates and costs vary by lender and property location. Stamp Duty Land Tax figures use England rates — Scotland (LBTT) and Wales (LTT) differ. Always consult an FCA-authorised mortgage adviser.