Mortgage Overpayment Calculator
✓ Verified for 2026/27Mortgage Details
£
%
Overpayment Details
£
£
Total Interest Saved
£27,840
by overpaying
Time Saved
5 yrs 4 mos
shaved off mortgage term
New Term Length
19 yrs 8 mos
instead of 25 years
Standard Payment
£1,112
required monthly payment
Interest Comparison
Total Principal Borrowed
£200,000
Standard Total Interest
£133,546
New Total Interest
£105,706
Total Saving
£27,840
New Interest
79%
Interest Saved
21%
How We Calculated This
- Model Standard Amortization: Calculate monthly payments based on loan balance, term, and rate.
- Apply Overpayments: Each month, add overpayment amount to principal reduction, which lowers interest in the following month.
- Calculate Savings: Sum total interest saved and calculate how many years and months are shaved off the original term.
Real-World Examples
Example: £200,000 mortgage at 4.5% over 25 years with £200/month overpayment
Models interest and time savings of overpaying.
Mortgage Balance: £200,000 Standard Term: 25 Years Standard Payment: £1,112/month Overpayment: £200/month Interest Saved: £27,840 Term Reduced by: 5 Years & 4 Months
Frequently Asked Questions
Is it better to overpay a mortgage or save?
If your mortgage interest rate is higher than the net interest rate you can earn on savings (after tax), overpaying your mortgage usually saves you more money.
Are there limits to how much I can overpay my mortgage?
Most UK lenders allow you to overpay up to 10% of your outstanding mortgage balance per year without penalty during a fixed-rate period.
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About This Calculator
This calculator uses the latest HMRC rates for the 2026/27 tax year. For illustrative purposes only — always consult a qualified tax adviser for formal advice.