Mortgage Repayment & Overpayment Calculator
Calculate monthly mortgage payments and see how much interest & years you save by overpaying.
🔒 Runs in your browser. Nothing you type is sent anywhere ✓ No email · No sign-up · No watermark · Free
Standard Monthly Payment £1,425.30 Total Interest: £177,589
Interest Saved by Overpaying £29,412 Saved! New Total Interest: £148,177
Time Cut Off Mortgage 3 yrs 6 mos earlier Paid off in 21 yrs 6 mos
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How to Use Mortgage Repayment & Overpayment Calculator
- Enter your Property Price / Loan Amount, Deposit, Interest Rate (%), and Mortgage Term (Years).
- Add an optional Monthly Overpayment (e.g. £150/month) to immediately see how much total interest you save and how many years/months earlier you become mortgage-free.
- Review the year-by-year balance reduction chart and amortisation breakdown.
How Mortgage Amortisation & Overpayments Save Tens of Thousands
In the early years of a standard 25- or 30-year repayment mortgage, the majority of your monthly payment goes toward paying interest rather than reducing the loan balance. Because any monthly overpayment goes 100% toward reducing the principal debt immediately, you stop paying compound interest on that slice of debt for the entire remainder of the mortgage term.
For example, on a £250,000 mortgage at 4.75% over 25 years, overpaying by just £150 per month cuts 3 years and 6 months off your mortgage and saves over £28,000 in interest.