Fortnightly vs Monthly Mortgage Calculator
See how switching Australian home loan repayments from monthly to genuine fortnightly instalments could shorten your loan term and cut total interest paid.
Your results
Strategy comparison
| Strategy | Annual paid | Payoff (years) | Total interest | Time saved | Interest saved |
|---|---|---|---|---|---|
| Monthly repayments | $36,748.14 | 30 | $602,444.16 | 0 mo | $0.00 |
| True fortnightly (annual total ÷ 26) | $36,748.14 | 30 | $600,916.62 | 0.5 mo | $1,527.54 |
| Half the monthly payment every fortnight | $39,810.48 | 24.4 | $469,568.89 | 67.4 mo | $132,875.27 |
Calculation breakdown
- Why half-monthly fortnightly pays off faster
- 26 fortnights a year × half the monthly payment = 13 full monthly payments a year, one extra payment vs 12 monthly payments
Assumptions
- "True fortnightly" simply divides the annual monthly total by 26, so the annual amount paid is unchanged.
- "Half the monthly payment every fortnight" pays 8.3% more each year, which is what accelerates payoff and cuts interest.
How this calculator works
Repayment frequency can make a bigger difference to your mortgage than many borrowers realise, but only if it's structured the right way. This calculator compares three strategies: standard monthly repayments, a 'true fortnightly' approach that simply divides the annual monthly total by 26 (which pays the same amount overall and makes little difference to your payoff timeline), and paying half your monthly repayment every fortnight instead. Because there are 26 fortnights in a year but only 12 months, paying half the monthly amount fortnightly means you make the equivalent of 13 monthly payments a year rather than 12 — an extra payment that goes straight toward reducing your principal. The calculator shows the payoff time and total interest for each strategy side by side, so you can see exactly how much time and money the genuine extra-payment approach could save compared with simply changing how often you pay the same annual amount.
Frequently asked questions
Does switching to fortnightly repayments always save interest?
Only if you pay half your monthly repayment every fortnight, which results in an extra payment each year. Simply dividing your annual repayments by 26 and calling it 'fortnightly' pays the same total and saves nothing.
How much extra do I actually pay with the half-monthly fortnightly strategy?
You end up paying 26 half-monthly instalments a year instead of 12 full monthly ones, which equals 13 monthly payments' worth — about 8.3% more per year — directed straight at reducing your loan balance faster.
Will my lender let me change repayment frequency without extra fees?
Most Australian lenders allow you to choose weekly, fortnightly or monthly repayments on an existing loan at no extra cost, but confirm with your lender since policies and any conditions can vary.
Results are estimates only and are not financial, tax, legal or credit advice.