Monthly repayment, total interest, and how many years (and pounds) you'd save by overpaying.
A repayment mortgage is worked out with the amortisation formula, a fixed monthly payment that covers the interest and gradually clears the balance. Early on, most of your payment is interest; later, most clears the loan.
Overpaying goes straight at the balance, so you pay interest on a smaller amount every month after, which is why even a modest overpayment can save years and tens of thousands in interest. Check your lender's annual overpayment limit (often 10% of the balance) to avoid early-repayment charges.
Illustrative; assumes a constant interest rate for the whole term (real mortgages re-fix periodically) and a repayment (not interest-only) mortgage.
Illustrative only, not financial or mortgage advice. Assumes a repayment mortgage at a constant rate; real rates change at the end of each fixed period. It doesn't include fees, insurance or early-repayment charges. Always check the details with your lender or a mortgage adviser.
Pairs with Net Worth Tracker.