Mortgage overpayment savings
Estimate how regular overpayments could reduce your total mortgage interest and shorten your term.
Results
These are estimates based on your inputs.
How this calculator works
We compare two amortisation schedules: one with standard monthly repayments and one with the same repayment plus your monthly overpayment.
The difference in total interest and months to repay gives interest saved and time saved.
What this calculator does
This calculator estimates how overpaying a mortgage can reduce total interest and shorten the remaining term.
It is useful when deciding whether overpayments are better than other uses for spare cash.
How the formula works
We calculate the standard monthly repayment, then simulate month-by-month balance changes with and without overpayment. Interest is charged on the outstanding balance each month.
Overpayments reduce principal faster, which lowers future interest and can cut years off the term.
Worked example
Example: £220,000 balance, 5% rate, 25 years remaining, £150 monthly overpayment. The calculator typically shows meaningful interest savings and a shorter repayment period.
Higher overpayments generally increase both interest savings and time saved.
Common mistakes
- Ignoring overpayment limits or fees in your mortgage deal.
- Using original mortgage amount instead of current balance.
- Assuming your rate will stay fixed for the whole term.
- Forgetting emergency savings before overpaying aggressively.
When to use this calculator
Use this when deciding how much to overpay and whether the benefits are worth it relative to other goals.
FAQs
Does this include early repayment charges?
No. Check your lender terms for overpayment limits and charges.
Should I reduce term or monthly payment?
This model assumes term reduction. Lenders may let you choose either approach.
Can I overpay one-off amounts?
This version uses a regular monthly overpayment. For one-offs, use scenario estimates.