When will you actually pay off your mortgage?
The short answer
A standard 30-year mortgage on a $700k AUD home finishes around year 30 if you pay the minimum. Add $200 a week, you cut roughly 7 years off. Add a full extra repayment once a year, you cut closer to 5. Pick a pace, see the date.
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The honest answer: mortgages move slowly until they don't
A 30-year mortgage feels like a forever number because the first decade is mostly interest. On a $560k loan at 6.1%, your first repayment puts about $2,840 toward interest and $560 toward the loan. After a full year, you've shifted around $7,000 of the balance. It feels like nothing.
By year 20, that flips. Most of each repayment is principal. The last five years move the balance faster than the first fifteen. The curve isn't linear, and that's what makes the "boring middle" so long.
How payoff math actually works
Worked example. Loan: $560,000. Rate: 6.1%. Term: 30 years. Standard fortnightly repayment: about $1,610. Over 30 years that's roughly $1.26M paid in total, of which about $700k is interest. The bank charges more interest than the house cost.
Drop the rate to 4.5% and total interest falls to about $460k. The same loan, a different decade, a $240k difference. This is why rate matters and why refinancing windows are worth checking yearly.
The three levers that change your payoff date: extra weekly, lump sums, refinance
Three things move the year. Extra weekly repayments. One-off lump sums (tax return, bonus, inheritance). And refinancing to a lower rate when one's available.
Of the three, extra weekly is the most boring and the most powerful. $200/week extra on the $560k example cuts the payoff by roughly 7 years and saves about $190k in interest. A $20k lump sum in year 3 saves about $45k. A 0.5% rate cut at refinance saves about $55k over the remaining term.
Biweekly vs fortnightly vs weekly. What actually changes
The "biweekly mortgage trick" you'll see online claims paying half your monthly amount every two weeks saves years. The mechanism: 26 fortnightly payments equals 13 monthly payments instead of 12. You're paying one extra monthly equivalent per year.
It works, but it's not magic. You can get the same result by adding 8% to your monthly payment. The frequency change just hides the extra inside the schedule. Either way, the lever is the same: more principal, earlier.
Compound interest works both ways. The bank's been doing it to you. Time to do it back.
The case for paying down vs investing the spare cash
Honest both-sides version. At a 6.1% mortgage rate, paying down is a 6.1% guaranteed return. Investing the same money in a broad index fund has averaged about 7% real return over the long run, but with volatility and no guarantee in any one decade.
The maths slightly favours investing. The psychology often favours paying down. The right answer depends on your risk tolerance, whether you have a buffer, and how much the certainty of "we own this house" is worth to you.
Try the calculator
Enter your balance, your rate, and your current weekly repayment. See your finish date. Then add $50 a week. Watch what happens. The leverage is usually bigger than people expect.
