Repayment calculator
Put in the loan amount, the interest rate and the term. The calculator shows the repayment, weekly, fortnightly or monthly, and the total interest over the loan. Add an offset balance or an extra repayment to see how much sooner the loan is paid off, switch to interest only to see what the repayment becomes when that period ends, or add a rate change to see the new repayment.
Work out your repayment
Darren Parker, Credit Representative 501592, authorised under Australian Credit Licence 389328. This is general information, not credit assistance.
What the repayment figure tells you, and what it doesn't
What it is. The repayment that pays off the loan amount you typed, at the rate you typed, over the term you typed. It's the arithmetic every lender uses, so on the same three figures it matches what a lender would quote.
What it isn't. An approval, or the rate you'll get. A lender sets the rate on your own file: your deposit, what the loan is for and how you repay. The figure is only as good as the rate you put in, so use a rate you've actually been quoted, and note the date you were quoted it.
What to have ready
The amount you're borrowing. Not the purchase price: the price less your deposit, plus any costs you add to the loan.
The interest rate. The rate on the loan, not the comparison rate, which bundles in fees and answers a different question.
The years left. For a loan you already have, the years still to run, not a fresh 30.
Principal and interest, or interest only. If interest only, how many years before it reverts.
How often you pay. Weekly, fortnightly or monthly.
Why interest only looks cheaper, and costs more
An interest-only repayment covers the interest and nothing else, so the balance doesn't fall. When the interest-only years end, you owe what you started with, over fewer years, so the repayment jumps.
An illustration, not a quote: $600,000 at 6.0% over 30 years. Principal and interest throughout is about $3,597 a month, with about $695,000 of interest over the loan. Five years of interest only is $3,000 a month, then about $3,866 a month for the remaining 25 years, with about $740,000 of interest in total: about $44,700 more.
Does paying fortnightly save money?
Only if you pay more. The calculator works out a true fortnightly repayment: the amount that clears the loan over the same term, paid 26 times a year. On the example above that's about $1,659 a fortnight, and the interest barely changes.
The saving people talk about comes from paying half the monthly repayment every fortnight, about $1,799 here. Over a year, that's 26 half-payments, the same as 13 monthly payments instead of 12. On the example, the loan is paid off in about 24 years and 6 months, with about $148,000 less interest. To see that in the calculator, choose fortnightly and put the difference, about $140 a fortnight, in the extra repayment box.
What an offset or extra repayments do
Both are illustrations on the same $600,000, 6.0%, 30-year loan.
An offset balance. Money held in an offset account is taken off the balance before interest is charged. With $30,000 held for the whole loan, it's paid off about 3 years sooner, with about $131,600 less interest. The calculator assumes the balance stays the same throughout.
An extra repayment. $200 a month on top of the repayment pays the loan off in about 26 years and 1 month, almost 4 years sooner, with about $106,700 less interest. Some fixed-rate loans limit extra repayments, so check yours before you plan on it.
If the rate changes
Put in the year the rate changes and the new rate, and the calculator works out the new repayment on what's left. On the same example, if the rate rises to 6.5% after two years, the repayment goes from about $3,597 to about $3,784 a month for the remaining 28 years.
What the calculator doesn't know
It's arithmetic on the figures you put in, not a lender's assessment and not an offer. It doesn't know what rate you'd be offered, whether a lender would approve the loan, or what fees come with it. It works the levers one at a time: an offset or extra repayment is worked on principal and interest, and a rate change is worked on its own, not combined with them. And it doesn't tell you how much you can borrow; that's a different question.
Repayment calculator questions
From three figures: the loan amount, the interest rate and the term. On principal and interest, each repayment covers that period's interest and pays off some of the balance, so the loan is cleared by the end of the term. On interest only, the repayment covers the interest alone.
Want the repayment run on a real rate?
Send me the loan amount, or your balance and years left if you already have a loan, and how you'd like to repay it. I'll run it at the rates lenders are offering for a file like yours, with principal and interest and interest only side by side if you're weighing them up.
You'll hear back within the hour in business hours, and by 9am the next business day after hours.
Updated 2 October 2026