Mortgage planning tool
Compare two amortisation schedules using an entered loan balance, rate and term. This is a planning comparison—not permission to exceed your loan's repayment terms.
See how much you can save by paying extra
The power of extra payments
Even small extra payments can save you thousands in interest and years off your loan. Use this calculator to see the impact of paying extra monthly, fortnightly, or making lump sum payments.
$73,891
Total over the life of the loan
3 years7 months
Loan paid off sooner
Check your loan's repayment and prepayment terms before changing automatic payments or making a lump sum.
Save FHBG requestMonthly payment = P × r(1+r)ⁿ ÷ ((1+r)ⁿ−1). Each month adds interest to the balance, then applies the scheduled payment, entered extra principal, and any due lump sum. Payments are modelled monthly; weekly and fortnightly extras are annualised into a monthly equivalent.
On $600,000 over 30 years at an entered 4.75%, the model estimates $526,758 total interest. Adding $200 each month estimates $452,867 interest and payoff 43 months earlier—a modelled $73,891 difference before fees or contract limits.
Deterministic FHBG amortisation model v1.0, reviewed 13 July 2026. Rate, term, balance and extras are user inputs. Verify current balance, rates, break fees, repayment limits and redraw treatment with the lender.
In a standard principal-and-interest model, earlier principal reduction lowers later interest. Your contract may limit, defer, or charge for extra payments, especially during a fixed term, so verify the actual loan terms first.
No. Frequency alone does not change the annual amount. Repayment time falls only when the total principal paid during the year increases or principal is paid earlier.
Yes. The model can apply one entered lump sum in the selected month. It does not model lender fees, limits, redraw, revolving-credit behaviour, tax effects, or future rate changes.