Free Tool · Australia · Best-in-Market
Mortgage Repayment Calculator
True fortnightly savings, extra repayments, offset impact, LMI estimate, and year-by-year amortisation — everything most calculators charge for, free.
True fortnightly savings, extra repayments, offset impact, LMI estimate, and year-by-year amortisation — everything most calculators charge for, free.
Estimates only. Actual repayments depend on your lender, fees, rate changes, offset use, and rounding conventions. LMI figure is an industry-average estimate — get a formal quote before settlement.
Australian home loans use the standard amortisation formula:
monthly = P × (r/12) ÷ (1 − (1 + r/12)−n) where P is the loan amount, r is the annual interest rate as a decimal, and n is the number of monthly periods (term × 12).
Each repayment covers the interest accrued on the outstanding balance, plus a slice of principal. Early in the loan most of your repayment is interest; later, most is principal. Total interest over a 30-year loan at 6.25% on $600,000 is approximately $730,000 — more than the original loan.
Most banks let you pay half your monthly repayment every 14 days. There are 26 fortnights per year, not 24, so this schedule delivers the equivalent of 13 monthly payments per year instead of 12. That extra month of principal compounds over the life of the loan.
On a $600,000 30-year 6.25% mortgage, switching from monthly to true fortnightly pays the loan off approximately 4-5 years earlier and saves around $110,000 in interest. This calculator simulates the actual fortnightly schedule and shows you the real saving, not just monthly ÷ 2.
An offset is a transaction account linked to your home loan. Interest is calculated each day on (loan balance − offset balance). Your scheduled repayment doesn't change, but a smaller portion goes to interest — so more goes to principal, accelerating payoff.
Keeping $20,000 in an offset on a $500,000 30-year 6.25% loan saves approximately $90,000 in interest over the life of the loan and pays it off about 1.5 years earlier — without changing your monthly cash-flow at all. It's the equivalent of a guaranteed after-tax return at your home loan rate.
If your loan-to-value ratio (LVR) exceeds 80% you'll typically pay LMI — a one-off premium that protects the lender (not you) if you default. LMI is usually capitalised onto the loan, so you pay interest on it for the life of the loan.
This calculator uses the following industry-average tiers as a starting estimate:
| LVR band | LMI estimate |
|---|---|
| ≤ 80% | No LMI |
| 80–85% | ~0.8% of loan |
| 85–90% | ~1.9% of loan |
| 90–95% | ~3.4% of loan |
| 95–97% | ~4.3% of loan |
Actual LMI is quoted by the insurer (Helia, QBE) based on your loan size, LVR, property type, and borrower profile. First home buyers using the federal First Home Guarantee Scheme avoid LMI entirely with a 5% deposit — check your eligibility.
Principal + Interest (P&I) is standard for owner-occupiers. Every repayment reduces the loan balance.
Interest Only (IO) means you only pay interest for a fixed period (typically 1–5 years), then revert to P&I over the remaining term. IO is popular with investors for tax purposes — the interest is fully deductible — and for short-term cash-flow management. The catch: when IO ends, the same principal must be repaid over a shorter remaining term, so the P&I monthly is materially higher than if you'd been on P&I from day one.
Example: $400,000 loan, 5 years IO, 30-year total term, 6.75% rate. IO monthly = $2,250. After 5 years the remaining 25 years pay off the full $400,000 — P&I monthly = $2,775 (~23% higher than IO).
On a $500,000 30-year P&I loan at 6%:
Variable-rate loans generally allow extra repayments without penalty. Fixed-rate loans often cap extras (commonly $10,000/year) during the fixed term — check your contract.
Banks usually round the monthly repayment to the nearest dollar or 10 cents. Some lenders use a 365.25/12 day convention versus 365/12, producing a daily-rate that's 0.05–0.10 bp different. ANZ, Westpac, CommBank and NAB also have slightly different "first payment" handling (interest accrual from settlement date vs first scheduled payment date). These factors typically move the monthly figure by less than $10 on a $600,000 loan.
Variable rates in Australia are pinned to the RBA cash rate. As of early 2026, the cash rate target is in the high-3% band after the 2024-25 cutting cycle. Owner-occupier variable rates from the big four are typically cash rate + 2.0% to 2.5%, putting headline rates around 5.99–6.49%. Investor rates carry a 30-50 bp premium.
APRA's serviceability buffer (3% above the contract rate, in effect since October 2021) is the biggest single driver of how much you can borrow — see our Borrowing Power Calculator.