Switching from monthly to fortnightly repayments is one of the easiest ways to save tens of thousands of dollars on your mortgage — and most borrowers have no idea it works or why.
Here's the full explanation, with the actual numbers.
It's not magic — it's maths. Here's the key insight:
There are 12 months in a year, but 26 fortnights. If you pay half your monthly repayment every fortnight, you end up making the equivalent of 13 monthly repayments in a year instead of 12. That one extra payment goes straight off your principal every year — and since interest is calculated on your outstanding balance, a lower balance means less interest every single day after that.
| Repayment Type | Payment Amount | Total Interest Paid | Loan Paid Off In |
|---|---|---|---|
| Monthly | $3,451/month | $642,360 | 30 years |
| Fortnightly | $1,726/fortnight | $578,200 | 27 years 1 month |
Based on $600,000 loan at 6.00% p.a. over 30 years. Figures are illustrative.
💰 Result: $64,160 saved in interest, and you own your home almost 3 years earlier — just by changing when you pay, not how much.
Technically yes — there are 52 weeks in a year, so weekly repayments (at one quarter of your monthly amount) give you the equivalent of 13 months of payments too. In practice, the difference between weekly and fortnightly is tiny. Most people find fortnightly easier to manage because it aligns with pay cycles.
Watch out for this. Some lenders offer "fortnightly" repayments that are simply your monthly payment divided by two, then debited 24 times a year (not 26). This doesn't give you the extra payment benefit — you end up paying exactly the same as monthly.
True fortnightly repayments = monthly repayment ÷ 2, paid 26 times per year. Always confirm with your lender which method they use.
It depends. Many fixed rate loans restrict extra repayments — some cap them at $10,000 per year. Since fortnightly repayments effectively make extra principal payments, check with your lender whether this is permitted under your fixed loan terms. Variable rate loans almost never have this restriction.
Use our free repayment calculator to compare monthly, fortnightly, and weekly options on your loan amount and rate.