Mortgage Overpayment Calculator UK 2026
Instantly calculate how much interest you can save and how early you can pay off your UK mortgage with monthly or lump sum overpayments. Perfect for homeowners looking to become debt-free faster.
Mortgage Overpayment Calculator
See how much you can save by overpaying your UK mortgage
The total amount you are borrowing for your mortgage.
Your current annual mortgage interest rate.
The original length of your mortgage in years.
The extra amount you plan to pay each month towards your capital.
Choose how many decimal places to show in results.
Your Mortgage Savings Projection
Interest saved, time saved, and detailed amortization breakdown
Enter your mortgage details above and click Calculate Savings to see how much you can save by overpaying.
Common Overpayment Scenarios
See how different monthly overpayments affect a £200,000 mortgage at 5% interest over 25 years.
| Monthly Overpayment | New Mortgage Term | Total Interest Paid | Interest Saved |
|---|---|---|---|
| £0 | 25 years | £150,754 | £0 |
| £50 | 23 yrs 1 mo | £137,340 | £13,415 |
| £100 | 21 yrs 6 mos | £126,249 | £24,505 |
| £200 | 18 yrs 10 mos | £108,911 | £41,843 |
| £300 | 16 yrs 10 mos | £95,922 | £54,833 |
| £500 | 13 yrs 11 mos | £77,652 | £73,102 |
Mortgage Overpayment Calculator FAQ
Everything you need to know about overpaying your UK mortgage, saving interest, and becoming debt-free faster.
Overpaying your mortgage reduces your outstanding capital balance faster. Since UK mortgage interest is calculated on the remaining balance, a lower balance means less interest is charged over time. This saves you thousands of pounds and can shorten your mortgage term significantly.
Yes, most UK mortgage lenders allow penalty-free overpayments of up to 10% of the outstanding balance per calendar year. If you overpay more than this allowance, you may be charged an Early Repayment Charge (ERC). Always check your specific mortgage terms.
It depends on your mortgage interest rate versus potential investment returns. If your mortgage rate is higher than what you expect to earn from investments (after tax), overpaying the mortgage is usually the better financial choice. If your mortgage rate is very low, investing might yield higher returns.
UK mortgage interest is typically calculated daily based on the annual interest rate divided by 365, then applied to your outstanding daily balance. It is then deducted from your monthly payment, with the remainder going towards reducing the capital.
Yes, you can make lump sum overpayments using savings, bonuses, or inheritance. Like regular monthly overpayments, lump sums usually count towards your annual penalty-free allowance (typically 10% of the balance).
By default, most UK lenders will reduce the mortgage term while keeping your monthly payment the same, which saves the most interest. However, some lenders allow you to choose to reduce your monthly payments instead, keeping the original term.