Mortgage Overpayment Calculator
Enter your outstanding balance, interest rate, and how much extra you can pay each month. See exactly how many months you cut off and how much total interest you save - with a chart comparing both schedules. Nothing uploaded.
Balance Over Time
Learn more: mortgage overpayment and interest savings
Why overpayment calculators matter - seeing your savings
On a typical UK mortgage, an extra £100 per month saves around £8,000-15,000 in interest and cuts 2-3 years off the term. The exact figure depends on your balance, rate, and term. The most important thing a mortgage overpayment calculator can show you is the side-by-side balance curve: your standard repayment line and your overpayment line on the same chart, so you can see the years you are buying back. This calculator shows you precisely how many months you cut and the interest saved in pounds.
Is it worth overpaying your mortgage?
Overpaying gives a guaranteed return equal to your mortgage interest rate - currently 3-6% for most UK fixed-rate deals. If your rate is below 4%, investing in a stocks ISA may outperform long-term but with more volatility. Above 5%, overpaying is often the better risk-adjusted choice. You can also combine a lump sum payment (applied immediately) and a regular monthly overpayment to see the combined effect on your payoff date and total interest.
Early Repayment Charges and flexibility
An Early Repayment Charge is a penalty if you exceed your annual overpayment allowance (usually 10% of the outstanding balance) during a fixed-rate period. Check your mortgage terms before making large lump sum payments. This calculator does not apply ERCs automatically - check your deal first. It models both a one-off lump sum payment and a regular monthly overpayment so you can see the impact of either or both together.
FAQ
Is it worth overpaying my mortgage?
Overpaying gives a guaranteed return equal to your mortgage interest rate - currently 3-6% for most UK fixed-rate deals. If your rate is below 4%, investing in a stocks ISA may outperform long-term but with more volatility. Above 5%, overpaying is often the better risk-adjusted choice. This calculator shows the exact pounds and months saved for your specific situation.
What is an ERC on a mortgage?
An Early Repayment Charge is a penalty if you exceed your annual overpayment allowance (usually 10% of the outstanding balance) during a fixed-rate period. Check your mortgage terms before making large lump sum payments. This tool does not apply ERCs automatically - check your deal first.
Can I make a lump sum payment as well as monthly overpayments?
Yes. This calculator models both a one-off lump sum payment (applied immediately) and a regular monthly overpayment. You can enter both together to see the combined effect on your payoff date and total interest.