Our free Mortgage Overpayment Calculator shows how overpaying could reduce your term and save you interest. Answer four quick questions for an instant comparison between your mortgage with and without extra monthly payments.
Your answers — tweak any number and update
This is an estimate for illustration only, based on your rate staying the same for the full term. Real mortgage rates usually change at the end of a fixed period, and some lenders cap how much you can overpay each year without a fee — check your mortgage terms before overpaying. This is not financial advice.
Mortgage Overpayment Calculator FAQs
Does this include early repayment charges?
No. Many UK lenders cap penalty-free overpayments, commonly around 10% of your balance per year. This calculator shows the potential savings assuming no penalties apply, so always check your specific mortgage terms before overpaying. Read our full guide for more detail.
Does my interest rate change over time in this calculation?
No, we assume your rate stays the same for the whole term for simplicity. In reality, most UK mortgages only fix for 2 to 5 years before moving to a new rate, so treat longer-term results as a rough guide rather than an exact prediction.
What if I want to try a one-off lump sum instead of monthly overpayments?
This calculator currently models regular monthly overpayments rather than a single lump sum. As a rough workaround, you could try entering a high monthly figure for a short period to approximate a similar effect. A dedicated lump-sum option may be added in future.
Is my information stored anywhere?
No. Every calculation happens entirely in your own browser, we don’t see, collect, or store any of the numbers you enter. See our Privacy Policy for more detail.