Overpayment Mortgage Calculator
See how much time and interest a monthly or one-off overpayment could save on your mortgage, compared to your standard repayment schedule.
Optional. Defaults to the standard scheduled payment for your balance/rate/term.
Extra amount paid on top of your regular payment each month
A single lump sum paid off the balance today
Overpayment impact
Time Saved
2 years, 3 months
Without overpayments
With overpayments
Assumes a fixed interest rate for the whole remaining term. Some mortgage deals cap the amount you can overpay each year (often 10% of the balance) without an early repayment charge - check your mortgage terms before overpaying.
Why overpaying works
Every mortgage payment is split between interest (charged on your current balance) and capital (which actually reduces what you owe). An overpayment goes entirely towards capital, which means every month after that, interest is calculated on a smaller balance - so the saving compounds over the life of the mortgage, not just in the month you make it.
Check your mortgage's overpayment limit
Most fixed-rate deals allow penalty-free overpayments up to a set percentage of the balance each year, commonly around 10% - overpaying beyond that can trigger an Early Repayment Charge. This calculator doesn't know your specific mortgage terms, so check your offer documents or ask your lender before making a large overpayment.