Weekly vs fortnightly mortgage repayments: does it save you?
Paying fortnightly instead of monthly can quietly knock years off your loan. Here's the trick behind it.
Last updated 3 November 2026
Switching your home-loan repayments from monthly to fortnightly is one of the oldest tricks for paying off a mortgage faster — and it genuinely works. But only if you do it the right way. Here’s the mechanism, and the catch.
The trick: 26 is more than 12 × 2
A year has 12 months but 26 fortnights. If you take your monthly repayment, halve it, and pay that half every fortnight, then over a year you make:
- 26 × (half a monthly payment) = 13 months’ worth of repayments
That’s one extra month every year, paid without really feeling it. And because the extra lands on your principal, it reduces the balance that interest is charged on — compounding the saving over the life of the loan. On a typical 30-year loan, true fortnightly repayments can cut several years off the term and tens of thousands in interest.
The catch: how the lender splits it matters
This is where people get caught. There are two ways a lender can set “fortnightly”:
- Half the monthly payment (good). 26 × half = 13 months a year. You pay extra, and you save.
- Annual amount ÷ 26 (no benefit). This just spreads the same 12 months across 26 payments. You pay the identical total each year and save nothing beyond a tiny timing effect.
So the saving doesn’t come from the frequency — it comes from paying more per year. When you set up fortnightly repayments, make sure each one is half your monthly figure, not the lender’s reduced “equivalent”.
Weekly vs fortnightly
Weekly works the same way: pay a quarter of the monthly amount every week (52 payments) and you again cover 13 months a year. The difference between weekly and fortnightly is tiny — paying a little more often trims interest marginally because the balance falls slightly sooner, but the big win is the extra month, which both achieve.
The simplest way to think about it
You don’t need a special schedule at all — making one extra monthly repayment a year, or adding a little to every payment, gives the same result. Fortnightly payments are just an automatic way to do it painlessly.
See exactly how much time and interest a faster schedule or extra repayments save on your loan with our mortgage repayment calculator, or how an offset balance compares.
Work out your own numbers
Frequently asked questions
Do fortnightly mortgage repayments actually save money?
Only if you pay exactly half the monthly amount each fortnight. There are 26 fortnights in a year, so 26 half-payments equal 13 monthly payments — one extra month of repayments a year. That extra goes straight onto the principal, cutting both the interest and the loan term. If the lender instead divides the annual amount by 26, you pay the same total and save nothing.
Is weekly better than fortnightly?
The saving is almost identical. What matters is paying more than 12 months' worth per year, not the frequency itself. Weekly (half the fortnightly, 52 times) and true fortnightly (half the monthly, 26 times) both add roughly one extra month a year. Slightly more frequent payments shave interest marginally because the balance drops a little sooner.
Why does paying fortnightly add an extra month?
A year has 12 months but 26 fortnights. If your fortnightly payment is half the monthly figure, 26 × half = 13 months of repayments, not 12. That 13th month each year is the extra that pays down your loan faster.
Can I just make extra repayments instead?
Yes — the benefit comes from paying more, not from the schedule. Making one extra monthly payment a year, or adding a bit to each repayment, achieves the same result. Fortnightly payments are just an easy, automatic way to do it without noticing.