Home Loan Repayment Calculator

How are home loan repayments calculated?

Repayments are worked out by spreading the loan plus interest evenly across the term, a process called amortisation. Each repayment covers the interest for the period plus a slice of the principal. Early in the loan most of the payment is interest, and as the balance falls, more of each payment goes to principal. The three inputs that set the repayment are the loan amount, the interest rate, and the loan term.

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Because the early years are interest-heavy, the rate you pay has an outsized effect on the total cost. The calculator above shows not just the repayment but the total interest, which is the number most people never see until years into a loan.

What changes your repayment?

Three levers move your repayment: the loan amount, the interest rate, and the term. A larger loan or a higher rate raises the repayment. A longer term lowers the repayment but increases the total interest, because you are borrowing the money for longer. A shorter term does the reverse, lifting the repayment but cutting total interest sharply.

Weekly, fortnightly, or monthly?

Paying more frequently reduces the total interest, because you bring the balance down sooner and more often. The most common acceleration approach is to pay half the monthly amount every fortnight. Because there are 26 fortnights in a year, that quietly adds the equivalent of an extra month of repayments annually, which can take years off the loan and save a large amount of interest.

Switch the toggle on the calculator between monthly, fortnightly, and weekly to see how the per-payment figure changes. Aligning repayments with your pay cycle also makes budgeting easier, since the money leaves your account around the same time it arrives.

Why the rate matters most

Of all the levers, the interest rate is the one with the biggest long-term effect that you can actually negotiate. On a $500,000 loan over 30 years, a rate just 0.5% lower saves roughly $57,000 in interest across the life of the loan. That is a substantial sum, and it comes from a difference most borrowers would barely notice on a rate sheet.

The advertised rate is rarely the best rate available. Lenders price for the customer who does not negotiate, and the gap between that rate and a sharp, broker-secured rate is where a large part of that saving sits. Knowing your repayment is step one. Knowing whether your rate is competitive is step two.

How to reduce your repayments

There are three main ways to reduce a repayment: secure a lower rate, extend the term, or restructure the loan. A lower rate is the best of the three, because it cuts the repayment and the total interest together. Extending the term lowers the repayment but increases total interest, so it eases monthly pressure at a long-term cost. Refinancing to a better rate is often the most effective single move.

Beyond the headline repayment, features like an offset account and the ability to make extra repayments can reduce the interest you pay without changing your required payment. The right structure depends on your goals, whether that is the lowest possible repayment now or paying the loan off as fast as possible.