Mortgage Overpayment Calculator
See how much interest you'd save — and how many years you'd shave — by overpaying.
Interest you could save
Add a monthly amount or lump sum and see how much interest you'd dodge.
How it works
We work out your standard monthly payment from your balance, interest rate and remaining term, then simulate the mortgage month by month with your extra payments on top.
In general:
- Every extra payment reduces your balance straight away, so less interest builds up next month.
- A lump sum has the biggest impact when paid early in the term.
- Even small regular overpayments can knock years off your mortgage.
This helps you decide whether to overpay now, save the money, or invest it instead.