Mortgage Overpayment Calculator UK
Estimate how much interest you could save and how many years you could shave off your mortgage by making regular overpayments.
Calculator
What this means
Overpaying your mortgage reduces the balance faster, cutting total interest and potentially shortening your mortgage term significantly.
How to use this calculator
- Enter your mortgage balance, rate and remaining term.
- Add a regular or one-off overpayment.
- See the interest saved and time cut from your mortgage.
Worked example
Overpaying £150 a month on a £180,000 mortgage at 4.5%.
- Overpayments reduce the balance that interest is charged on.
- This shortens the term and cuts total interest.
You'll see how many years and how much interest the overpayment saves.
Who this is for
- Homeowners with spare monthly income.
- Anyone with a lump sum deciding how to use it.
- People wanting to be mortgage-free sooner.
Why overpaying saves so much
Because mortgage interest is charged on the outstanding balance, overpayments reduce that balance and save interest for the rest of the term — often far more than the overpayment itself.
Most lenders allow you to overpay up to 10% of the balance each year without penalty. Check for early repayment charges, especially during a fixed-rate deal.
Frequently asked questions
Many lenders allow up to 10% overpayment per year without penalty on fixed-rate deals. Check your mortgage terms.
Compare your mortgage interest rate with savings returns after tax. Often overpaying a high-rate mortgage wins.
No. Early repayment charges are not included in this estimate.
Many lenders let you overpay up to 10% of the outstanding balance per year penalty-free. Above that, early repayment charges may apply, particularly on fixed-rate deals.
If your mortgage rate is higher than the interest you'd earn on savings, overpaying usually wins. Keep an emergency fund first, as overpayments can be hard to get back.
Disclaimer
This calculator provides estimates for guidance only. It is not financial, legal or tax advice. Always check official sources or speak to a qualified professional before making decisions.
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