Mortgage Overpayment Calculator
See how much a regular overpayment cuts from a mortgage: months saved, interest saved and the new payoff date. Works for any loan in any currency.
💼 Are you a real estate agent or broker? Send this calculator to your buyers on your own branded listing page — every enquiry comes straight to your WhatsApp. Create free agent page →Overpaying is the highest-return, lowest-risk move most borrowers have, and it is badly under-used because the benefit is invisible until you compute it. Every extra unit of currency goes straight against the balance, so it removes all the future interest that balance would have produced.
The effect compounds backwards. Money paid in year one avoids interest for the whole remaining term; the same amount in the final year avoids almost none. That is why small, early overpayments beat large, late ones.
How it is worked out
There is no shortcut formula — the loan is re-run month by month with the larger payment: balance = balance × (1 + i) − (payment + extra), repeated until the balance reaches zero. The number of iterations is the new term.
Worked example
A 250,000 balance at 6.5% with 22 years left has a payment of about 1,782 and roughly 220,500 of interest still to come. Adding 200 a month clears it in 17 years 9 months — more than four years early — and saves about 48,800 in interest for 42,600 of extra payments, most of which is principal you owed anyway.
Reduce the term, not the payment
Most lenders will apply an overpayment by lowering the monthly figure while keeping the term. That feels like a saving and mostly is not. Ask explicitly for the term to be shortened instead — that is where the interest saving in this calculator comes from.
Turn a calculation into an enquiry
Buyers who run these numbers are ready to talk. Give every listing its own page with your photo, phone and WhatsApp on it — leads land straight on your phone.
Create your free property pageFrequently asked questions
Is it better to overpay monthly or in a lump sum?
Both work, and what matters most is how early the money arrives. A lump sum in year two beats the same amount spread across the final five years. Monthly overpaying is simply easier to sustain than saving for a lump sum.
Will my lender charge me for overpaying?
It depends on the product. Variable-rate loans to individuals are frequently penalty-free, while fixed deals often allow a set annual percentage before charges apply. Check the agreement before starting, because an early-repayment charge can exceed the saving.
Should I overpay or invest the money instead?
Overpaying gives a guaranteed return equal to your interest rate. An investment does not, so a small edge in expected return is not automatically better once you account for risk. Clear higher-rate debt first either way.