Mortgage Overpayment Calculator
See how much interest and time you save by overpaying your mortgage every month.
Your result
Updates as you type. Based on 2025/26 UK figures where relevant.
How this is worked out
We run your mortgage month by month with the extra payment added, then compare total interest and term against the standard schedule.
Tips
- Stamp duty rules differ by nation: SDLT in England and Northern Ireland, LBTT in Scotland and LTT in Wales.
- Lenders price mortgages in LTV bands, so a slightly bigger deposit can unlock a noticeably lower rate.
- Always compare the total cost of a mortgage deal including fees, not just the headline rate.
Guides for this calculator
- How to Calculate Mortgage Overpayments in the UK: Step-by-Step Guide
- Mortgage Overpayments: Common Mistakes, Tips and FAQs
More property and mortgages calculators
Frequently asked questions
How does the mortgage Overpayment Calculator work?
We run your mortgage month by month with the extra payment added, then compare total interest and term against the standard schedule.
Do these calculators cover Scotland and Wales?
Yes. We have separate calculators for LBTT in Scotland and Land Transaction Tax in Wales, as well as SDLT for England and Northern Ireland.
Are the mortgage figures a mortgage offer?
No. They are estimates. A lender's decision depends on your credit history, outgoings and their own affordability checks.
How accurate is the monthly repayment?
It uses the standard repayment formula and matches lender illustrations closely for a fixed rate, but actual payments can vary if your rate changes.
This calculator gives an estimate for general information. It isn't financial, tax, legal or medical advice. Check official figures on GOV.UK or NHS.uk, or speak to a qualified adviser.