Free Australian Finance Calculators
Estimate repayments, total interest and the impact of extra payments or an offset account.
Optional — Reduce your interest
Min. repayment per month
$3,636
Calculations assume a fixed rate for the full term. Rates and fees vary by lender. Not financial advice.
The two most powerful tools for cutting your interest bill are an offset account and extra repayments. Both reduce the principal your interest is calculated on — the difference is that offset funds remain accessible while extra repayments permanently reduce your balance.
Switching from monthly to fortnightly repayments is one of the easiest wins — you make 26 half-payments per year (equivalent to 13 monthly payments) with no noticeable change to your budget.
Australian mortgage repayments use the standard amortisation formula. Each repayment covers the interest accrued since the last payment, with the remainder reducing the principal. You can use the calculator above to see your exact repayment for any loan amount, rate and term.
Paying weekly or fortnightly saves thousands in interest. With a fortnightly schedule you make 26 half-payments per year — equivalent to 13 monthly payments instead of 12. On a $600,000 loan at 6% over 30 years, switching from monthly to fortnightly payments saves approximately $35,000 in interest and cuts ~3 years off the loan.
An offset account is a transaction account linked to your home loan. The balance is subtracted from your loan balance before interest is calculated. For example, with a $500,000 loan and $50,000 in your offset account, you only pay interest on $450,000 — while keeping your savings fully accessible.
On a $600,000 loan at 6.1% over 30 years, paying an extra $500/month reduces total interest by approximately $127,000 and cuts 9 years off the loan. Use the extra repayment field in the calculator above to see your exact savings.
Yes — most variable rate mortgages allow unlimited extra repayments. Fixed rate loans typically cap extras at $10,000–$30,000/year with break fees above the limit. Always check your loan contract terms before making large lump-sum repayments.
Variable rates in 2025 typically range from 5.5% to 7.5% depending on lender, LVR and loan features. Fixed rates vary by term. The best way to find a competitive rate is to compare lenders or use a mortgage broker. The calculator defaults to 6.1% as a mid-range estimate.
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