Mortgage calculator Australia
Calculate your home loan repayments and see how extra payments can save you thousands in interest and years off your mortgage. Weekly, fortnightly, and monthly options.
Principal you intend to borrow.
Headline rate — comparison rate may differ.
Interest-only repayments switch to principal and interest after the selected period.
Adds on top of every scheduled payment; reduces total interest.
Amortisation schedule
| Period | Payment | Principal | Interest | Balance |
|---|---|---|---|---|
| 1 | $3,062.34 | $479.01 | $2,583.33 | $499,520.99 |
| 2 | $3,062.34 | $481.49 | $2,580.86 | $499,039.50 |
| 3 | $3,062.34 | $483.97 | $2,578.37 | $498,555.53 |
| 4 | $3,062.34 | $486.47 | $2,575.87 | $498,069.05 |
| 5 | $3,062.34 | $488.99 | $2,573.36 | $497,580.07 |
| 6 | $3,062.34 | $491.51 | $2,570.83 | $497,088.55 |
| 7 | $3,062.34 | $494.05 | $2,568.29 | $496,594.50 |
| 8 | $3,062.34 | $496.61 | $2,565.74 | $496,097.89 |
| 9 | $3,062.34 | $499.17 | $2,563.17 | $495,598.72 |
| 10 | $3,062.34 | $501.75 | $2,560.59 | $495,096.97 |
| 11 | $3,062.34 | $504.34 | $2,558.00 | $494,592.62 |
| 12 | $3,062.34 | $506.95 | $2,555.40 | $494,085.67 |
| 355 | $3,062.34 | $2,969.11 | $93.24 | $15,077.22 |
| 356 | $3,062.34 | $2,984.45 | $77.90 | $12,092.78 |
| 357 | $3,062.34 | $2,999.87 | $62.48 | $9,092.91 |
| 358 | $3,062.34 | $3,015.36 | $46.98 | $6,077.55 |
| 359 | $3,062.34 | $3,030.94 | $31.40 | $3,046.60 |
| 360 | $3,062.34 | $3,046.60 | $15.74 | $0.00 |
Each mortgage repayment consists of two parts: principal (paying down the loan) and interest (the cost of borrowing). In the early years, most of your payment goes to interest. As the loan balance decreases, more goes to principal.
Principal & Interest (P&I)
The standard loan type. Each payment reduces your loan balance and covers interest. Most owner-occupier loans are P&I.
Interest Only (IO)
You only pay interest for a set period (usually 1–5 years). The loan balance doesn't decrease. Often used by investors.
Making extra repayments is one of the most effective ways to pay off your mortgage faster. On a $500,000 loan at 6.2% over 30 years:
Extra $100/month
~$60,626
interest saved · 2.5 years early
Extra $200/month
~$108,828
interest saved · 4.6 years early
Extra $500/month
~$209,582
interest saved · 9.1 years early
Frequency and annual repayment amount are separate choices. A standard lender-calculated schedule can still run for the full term; the faster method deliberately pays the equivalent of one extra monthly repayment each year.
Setting your fortnightly repayment to exactly half your monthly amount — rather than a quarter of an annual figure — is the trick that makes fortnightly repayments save real money. Because there are 26 fortnights in a year, you end up making the equivalent of 13 monthly payments instead of 12, with the extra payment going straight to principal.
Monthly (12/yr)
$3,062.34
30 years · $602,444 total interest
Half-monthly fortnightly (26/yr)
$1,531.17
~24.4 years · ~$469,574 total interest
On a $500,000 loan at 6.2% over 30 years, paying half your monthly repayment every fortnight pays the loan off roughly 5.6 years sooner and saves about $132,870 in interest compared with the standard monthly schedule. See our fortnightly vs monthly repayments guide for the full breakdown, including why some lenders' "fortnightly" default doesn't actually deliver this saving.
Every mortgage repayment splits between interest and principal, and that split changes across the life of the loan. In the early years, most of each repayment covers interest on the large outstanding balance — on a $500,000 loan at 6.2%, the very first monthly repayment of $3,062.34 is $2,583.33 interest and just $479.01 principal.
As the balance falls, the interest portion of each repayment shrinks and the principal portion grows, until the two cross over — typically past the halfway point of a 30-year term. This is why extra repayments made early in the loan have an outsized effect: every dollar of extra principal in year one stops accruing interest for the remaining 29 years.
Run your own numbers and see the full month-by-month interest/principal split below the calculator above, or read our amortisation schedule guide for a worked walkthrough.
Indicative monthly principal & interest repayments at 6.2% p.a. over a 30-year term, for common loan sizes:
| Loan amount | Monthly repayment |
|---|---|
| $300,000 | $1,837 |
| $500,000 | $3,062 |
| $750,000 | $4,594 |
| $1,000,000 | $6,125 |
Based on the reference rate in the calculator above (6.2% p.a., last reviewed 2026-08-23). Your actual rate depends on your lender, LVR, and loan type — use the calculator to model your own figures.
Both levers cut the interest you are charged by shrinking the balance interest is calculated on. Deploy the same dollar at the same moment and the interest saving is identical — the schedules below are run on the same engine to show it. The real decision is about access, tax and lender policy, not arithmetic.
| Strategy | Loan paid off in | Total interest | Interest saved |
|---|---|---|---|
| No offset, no extra repayments | 30.0 years | $602,444 | — |
| $50,000 sitting in an offset from day one | 23.1 years | $396,131 | $206,313 |
| $500 a month of extra repayments | 20.9 years | $392,862 | $209,582 |
| $500 a month accumulating in an offset | 20.9 years | $392,862 | $209,582 |
$500,000 principal and interest at 6.2% p.a. over 30 years, monthly repayments, constant rate. The last two rows are the same dollars on the same dates — hence the same result to the dollar.
Choose the offset when
You want the money back without asking permission — an offset balance is your own cash, withdrawable at any time. You might turn the home into a rental later: withdrawing from an offset is not a borrowing, so it leaves the deductible loan balance intact. Or you park an emergency fund, a tax bill or a bonus that you may need within the year.
Choose extra repayments when
The loan has no offset facility, or the offset carries a package fee that outweighs the interest saved on a small balance. Extra repayments also remove the temptation to spend the buffer, and on many loans they are free while an offset is not. Check whether redraw is available and whether the lender caps or delays it.
The tax trap on redraw. If you later rent the property out, money you redraw from the loan is treated as a fresh borrowing and its deductibility depends on what you spend it on — redrawing for a car or a holiday turns the loan into a mixed-purpose account that has to be apportioned. A withdrawal from an offset account is not a borrowing at all, so the interest on the underlying loan is unaffected. If there is any chance the home becomes an investment property, the offset is the safer container for spare cash.
Model your own balance in the offset account calculator or the extra repayment calculator, and see the full comparison in the extra repayments and offset guide.
Monthly principal and interest repayments over a 30-year term, by rate and loan size. Lenders assess new applications at roughly three percentage points above the actual rate, so reading down a column is also a rough serviceability stress test.
| Rate | $300,000 | $500,000 | $750,000 | $1,000,000 |
|---|---|---|---|---|
| 5.5% | $1,703 | $2,839 | $4,258 | $5,678 |
| 6.0% | $1,799 | $2,998 | $4,497 | $5,996 |
| 6.2% (reference) | $1,837 | $3,062 | $4,594 | $6,125 |
| 6.5% | $1,896 | $3,160 | $4,741 | $6,321 |
| 7.0% | $1,996 | $3,327 | $4,990 | $6,653 |
| 7.5% | $2,098 | $3,496 | $5,244 | $6,992 |
On a $500,000 loan, moving from 6.2% to 7.0% adds about $264 a month; dropping to 5.5% saves about $223. Compare a switch end to end in the refinance calculator, which nets off discharge, application and valuation fees to give a break-even month.
How is mortgage repayment calculated?
How does the interest-only calculation work?
Do weekly or fortnightly repayments automatically save interest?
What is a comparison rate?
What is an offset account?
Should I fix my interest rate?
Should I pay my mortgage fortnightly or monthly?
Is an offset account better than extra repayments?
How much does my repayment change if rates rise?
Does putting $50,000 in an offset really save that much?
What is an amortisation schedule?
Tax Accuracy & Sources
Estimates principal-and-interest repayments using the standard PMT formula. For interest-only loans it models an initial IO period followed by principal-and-interest repayments over the remaining original term. Assumes a constant rate and does not account for lender fees, comparison rates, lenders mortgage insurance, offset accounts, or redraw facilities.