Based on Australian lending practices and 2026 data
Mortgage Repayment Calculator Australia (2026)
This mortgage calculator estimates repayments, stress signals, and lender-style assessment outcomes so you can evaluate home loan affordability before applying. It is built for Australian borrowers including first-home buyers, upgraders, refinancers, and investors who want clearer numbers than basic repayment tools. You can test principal and interest versus interest-only structures, compare repayment frequencies, and see how rate changes or extra repayments affect long-term cost. The model also reflects common Australian lending context: APRA-style serviceability buffers, bank assessment rates, and practical cashflow impacts from existing debt. Use it to pressure-test scenarios, understand trade-offs, and set a safer borrowing plan based on your own income and commitments.
How mortgage repayments are calculated
Repayments are driven by four inputs: loan amount, interest rate, loan term, and repayment frequency. For a principal and interest loan, each payment includes interest plus principal reduction. Early repayments are interest-heavy; later repayments reduce more principal as the balance falls.
P&I vs interest-only
Principal and interest (P&I) pays down the loan balance over time, usually resulting in lower total interest across the life of the mortgage. Interest-only repayments are lower at first, but principal does not reduce during the interest-only period. When that period ends, repayments can rise sharply.
Offset accounts explained
An offset account links your savings to your home loan and reduces the balance charged interest. For example, a $600,000 loan with $40,000 in offset is typically charged interest on $560,000. This can reduce interest cost while keeping your cash liquid for emergencies.
What banks assess
Lenders assess income quality, living expenses, existing debts, credit card limits, dependents, and repayment buffers. They focus on serviceability rather than just your current repayment comfort. You can also compare with our borrowing power calculator for a dedicated serviceability view.
APRA buffer explained
In Australia, banks commonly assess your loan at a higher rate than your contract rate (often +3.0%). This APRA-aligned servicing buffer is designed to test resilience if rates rise. It often reduces the amount you can borrow compared with simple repayment calculators.
Weekly vs monthly repayments
Weekly or fortnightly repayments can improve budgeting discipline and may reduce interest over time when they lead to earlier principal reduction. Monthly repayments are simpler to align with many salaries. The best option is the one you can sustain consistently without harming emergency cashflow.
Common mistakes
- Using headline rate only and ignoring comparison rate and fees.
- Assuming approval at contract rate rather than buffered assessment rate.
- Keeping high credit card limits that reduce borrowing power.
- Overestimating affordability without testing rate-rise scenarios.
- Ignoring state costs like stamp duty in total purchase budget.
FAQ
How is mortgage repayment calculated in Australia?
Repayment depends on loan amount, interest rate, term, and frequency. P&I loans progressively reduce principal while interest-only loans do not during the IO period.
Why do banks assess at a higher interest rate?
Lenders typically apply a serviceability buffer (commonly around +3%) to test affordability if rates rise.
Do credit card limits affect borrowing power?
Yes. Many lenders convert card limits into an assumed monthly commitment during servicing assessment.
Where can I estimate NSW stamp duty?
Use our NSW stamp duty calculator to model purchase costs.
Want to track this with your real spending?
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Jump between calculators to plan your full purchase picture.
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- Stamp Duty NSWTransfer duty, first home buyer relief, and total cost.
- Borrowing PowerIncome, expenses, APRA buffer, and loan sizing.
- Rent vs BuyLong-term net wealth comparison across buy vs rent scenarios.
- Negative Gearing ChangesYearly holding cost under illustrative proposed negative gearing rules.