How the repayment is worked out
For principal and interest, the monthly repayment uses the standard loan formula: the loan amount × r ÷ (1 − (1 + r)−n), where r is the yearly rate ÷ 12 and n is the number of months. Weekly and fortnightly figures are the monthly repayment × 12 ÷ 52 or 26, which is how most lenders and comparison sites show them.
Interest-only repayments are the loan amount × the yearly rate ÷ 12. When the interest-only period ends, repayments step up because the whole loan is then repaid over a shorter remaining term.
What it can't tell you
Real loans have fees, rate changes, offset accounts and different rules for extra repayments and redraw, especially on fixed rates. If a lender advertises an interest rate, it must also show a comparison rate, which includes most fees. Ask us for the comparison rate on any loan you're considering.
Wondering what you could borrow in the first place? Try the borrowing power estimate. Already have a loan? The refinance savings calculator compares two rates including switching costs.
Common questions
Is weekly or fortnightly better than monthly?
Here, weekly and fortnightly are simply the monthly repayment spread out, so the total is the same. Paying half your monthly repayment every fortnight means 13 monthly repayments a year instead of 12, which pays the loan off sooner. Check your lender allows it.
Why does my repayment jump after interest-only?
During interest-only you don't reduce the loan. When it ends, the full balance has to be repaid over the remaining years, so principal and interest repayments are higher than if you had paid principal from the start.
Is the rate in the calculator an offer?
No. It's an example you can change. We don't show lender rates here. A broker can show you real rates with their comparison rates.