Australia Mortgage Repayment Calculator: Weekly, Fortnightly and Monthly

Home loan repayments at a glance, October 2026

Australian home loan repayments rose through 2026 as the Reserve Bank of Australia lifted the cash rate four times, from 3.60% to 4.60% on 30 September 2026. At a 6.50% variable rate over 30 years, every $100,000 borrowed costs about $632.07 a month.

How much are repayments on a $500,000 mortgage?

Repayments on a $500,000 mortgage at 6.50% over 30 years are $3,160.34 a month, $1,457.93 a fortnight or $728.82 a week. Over the full term you would pay $637,722.44 in interest, more than the amount borrowed.

How are mortgage repayments calculated?

Mortgage repayments in Australia are calculated with the standard amortisation formula: a level repayment that pays each period's interest and clears the loan exactly at the end of the term. Early repayments are mostly interest; later repayments are mostly principal.

The formula is: repayment = L × r ÷ (1 − (1 + r)⁻ⁿ), where L is the loan amount, r is the yearly rate divided by the number of repayments a year, and n is the total number of repayments.

1. Rate per repayment. 6.50% ÷ 12 = 0.5417% a month.
2. Number of repayments. 30 years × 12 = 360 repayments.
3. Apply the formula. $600,000 × 0.005417 ÷ (1 − 1.005417⁻³⁶⁰) = $3,792.41 a month.
4. Interest each month. The first month's interest is $600,000 × 0.5417% = $3,250.00, so $542.41 reduces the balance.

Fortnightly and weekly repayments

For fortnightly and weekly repayments the same formula uses 26 or 52 repayments a year and the rate divided by 26 or 52. That gives $1,749.52 a fortnight and $874.58 a week on the $600,000 loan. Many lenders instead quote monthly × 12 ÷ 26 for fortnightly, which gives a near-identical $1,750.34.

Interest-only repayments

An interest-only repayment is simply the balance × the rate for the period: $600,000 × 6.50% ÷ 12 = $3,250.00 a month. When the interest-only period ends, the full balance is repaid over the years left, using the formula above.

How lenders charge interest

Australian lenders usually work out interest daily on the balance and charge it monthly. This calculator charges interest per repayment period, so a lender's figure can differ by a few dollars, but the total interest and payoff time are very close.

How to use the mortgage repayment calculator

1. Enter the loan amount. Use the amount you borrow: the price less your deposit, plus any lenders mortgage insurance added to the loan.
2. Enter the interest rate. Use the rate on your loan offer or statement, not the comparison rate.
3. Set the loan term. Use the years left on an existing loan, or 25 or 30 for a new one.
4. Pick the repayment frequency. Monthly, fortnightly or weekly. The receipt shows all three either way.
5. Choose the repayment type. Pick interest only first for an investment or construction loan, and set the interest-only years.
6. Add extra repayments or an offset. Enter an amount added to each repayment, or the savings you keep in an offset account.
7. Open More options if needed. Add a one-off lump sum and the year you pay it, or a monthly account fee.
8. Read and test the result. Check the balance chart and yearly schedule, try a rate change or a different term below the calculator, then download a PDF or CSV.

Example repayments on an Australian home loan

Each example uses the same model as the calculator, with principal and interest repayments and a constant rate unless stated.

Weekly vs fortnightly vs monthly repayments

Switching from monthly to true fortnightly or weekly repayments saves very little: on a $600,000 loan at 6.50% over 30 years, fortnightly saves $643.35 of interest and weekly saves $919.09. The large saving comes from paying half the monthly repayment every fortnight, which adds one extra monthly repayment a year.

Ask your lender which method it uses. If it sets fortnightly repayments at monthly × 12 ÷ 26, you can still get the faster payoff by paying half the monthly amount, as long as the loan allows extra repayments without a fee.

How interest rate and loan term affect the cost

A higher rate raises every repayment, and a longer term lowers repayments but adds far more interest. On $600,000, each 0.50 percentage point adds about $190 to $205 a month over 30 years, while a 25-year term costs $258.83 more a month than 30 years at 6.50% but saves $149,894.04 of interest.

What the 2026 rate rises mean for repayments

The Reserve Bank raised the cash rate by 0.25 percentage points in February, March, May and September 2026, taking it from 3.60% to 4.60%, its highest level since 2011. The big four banks passed the September rise on to variable rates from 9 October 2026.

One 0.25 point rise adds $98.11 a month to this loan; the full 1.00 point of 2026 rises adds $385.68 a month, or $4,628.16 a year. Use the rate change tool below the calculator to see your own figures.

Principal-and-interest vs interest-only loans

Principal and interest repayments reduce the loan from the first repayment; interest-only repayments cover just the interest, so the balance stays the same until the interest-only period ends. Interest-only repayments are lower at first but cost more over the life of the loan and rise sharply later.

Lenders usually charge a higher rate for interest-only loans, which widens the gap. Interest-only is most common on investment loans, where the interest is tax deductible; the rental property negative gearing calculator shows the tax side.

Extra repayments, offset accounts and redraw

Extra repayments and an offset account both cut interest because interest is charged on a smaller balance. Most variable loans let you make extra repayments without a fee; fixed-rate loans often cap them at a set amount a year, which varies by lender.

Offset account or extra repayments?

Each dollar in an offset saves the same interest as a dollar of extra repayment, but stays your savings: you can withdraw it at any time. Extra repayments reduce the balance, and getting them back depends on the loan's redraw facility, which a lender can restrict. An offset suits money you may need; extra repayments suit money you will not.

Does paying extra lower your repayment?

Usually not. Most lenders keep your scheduled repayment the same and the loan finishes sooner, which is how this calculator works. Some lenders will recalculate a lower repayment on request after a large lump sum.

Can you afford a rate rise? The 3% serviceability buffer

Australian lenders test whether you could still afford repayments if your rate rose by at least 3 percentage points, the serviceability buffer set by the Australian Prudential Regulation Authority (APRA). On a $600,000 loan at 6.50%, that means showing you can pay $5,045.13 a month at 9.50%, $1,252.72 more than the actual repayment.

The calculator shows your stress-test repayment in the receipt. If that figure would stretch your budget, a smaller loan, a longer term or a larger deposit reduces it. The buffer is a test, not a forecast of where rates will go.

What can change your actual home loan repayments?

Your real repayments can differ from this estimate when the rate changes, fees apply, or the loan's features change how interest is charged.

Rate changes

Variable rates move when lenders reprice, usually after a Reserve Bank decision, and your lender then sets a new repayment. A fixed rate stays the same for the fixed term, then reverts to a variable rate.

Fees and the comparison rate

Package fees, account fees and upfront fees raise the cost of a loan without changing the advertised rate. The comparison rate rolls most of these into one figure, but it is based on a $150,000 loan over 25 years, so it can overstate or understate the effect of fees on your loan size.

Lenders mortgage insurance

Borrowing more than about 80% of the property's value usually means paying lenders mortgage insurance (LMI). If it is added to the loan, enter the higher loan amount to see the repayment.

Fixed rate break costs

Repaying or refinancing a fixed loan early can trigger a break cost, which depends on how rates have moved since you fixed. Check your contract before making large extra repayments on a fixed loan.

Upfront purchase costs

Stamp duty and government transfer fees are paid at settlement and are not part of your repayments unless you borrow them. Use the stamp duty calculator Australia and check whether a first home buyer grant reduces what you need to borrow.

Common mortgage calculation mistakes

Most errors in home loan estimates come from using the wrong rate or the wrong frequency method. These are the ones that change the answer the most.

1. Using the comparison rate. The comparison rate includes fees on a $150,000 loan; enter the actual interest rate for repayments.
2. Halving the monthly and calling it fortnightly. $1,896.20 is not the true fortnightly repayment ($1,749.52); it is an extra $146.68 each fortnight that shortens the loan.
3. Dividing the yearly rate by 12 for weekly loans. Weekly repayments use the rate divided by 52.
4. Forgetting the interest-only jump. On $600,000 the repayment rises $801.24 a month when a 5-year interest-only period ends.
5. Ignoring the stress test. A lender assesses $5,045.13 a month on a $600,000 loan at 6.50%, not $3,792.41.
6. Treating the offset as a one-off. The saving assumes the balance stays in the offset; spending it reduces the saving.

How close is this estimate?

This mortgage repayment calculator gives the same repayment as the standard formula used across the industry, including the Moneysmart mortgage calculator, for a loan with a constant rate. A lender's figure may differ by a few dollars because interest is charged daily, and by more if fees, a rate change or a fixed-rate period apply.

It does not include lenders mortgage insurance unless you add it to the loan amount, upfront fees, changes to your offset balance over time, or a split loan with fixed and variable parts. Treat the result as a planning estimate and confirm repayments with your lender's loan contract.