Whether you’re buying your first home, upgrading to accommodate your growing family or downsizing after your kids have flown the coop, knowing how much your home loan is going to set you back is essential. Punching all the numbers into a simple-to-use mortgage repayment calculator like this one gives you a clear idea of what different loan sizes, terms and rates will cost each instalment and overall.
How to use the mortgage repayment calculator
Using the mortgage repayment calculator is easy. All you need to do is input your loan amount, interest rate, loan term, any fees from your lender (and their frequency) and how often you’re making your repayments.
Once you throw that information into the calculator, it’ll tell you what your weekly, fortnightly or monthly payments will be, as well as the overall amount you’ll pay in interest and fees. Note that this will give you the numbers inclusive of your loan debt, meaning it won’t work for interest-only home loans.
As you can see, there are several key variables that impact the cost of your mortgage. Let’s take a look at a few examples and see what impact they can have on how much you’re paying for your home loan:
Example #1: The importance of comparing interest rates
Olivia has had an offer accepted on a new $800,000 house, of which $200,000 will be paid as a deposit. It’s time for her to consider the different options available on the market for her home loan. She picks out a few offers and runs the numbers in the calculator to get the following:
| Loan amount | Loan term | Interest rate | Fortnightly payment | Total interest | |
|---|---|---|---|---|---|
| Lender A | $600,000 | 30 years | 5.25% p.a. | $1,529 | $592,183 |
| Lender B | $600,000 | 30 years | 5.35% p.a. | $1,546 | $605,590 |
| Lender C | $600,000 | 30 years | 5.50% p.a. | $1,572 | $625,831 |
| Lender D | $600,000 | 30 years | 5.70% p.a. | $1,607 | $653,060 |
| Calculations are for illustrative purposes only and may not be reflective of the interest rate you’re offered on your home loan. Calculations do not include loan fees or any other home-buying costs. | |||||
Olivia sees that even the jump from 5.25% p.a. to 5.50% p.a. would cost her almost $34,000 more across the life of her loan. She decides to go with Lender A in this instance.
Example #2: Tossing up the term length
Troy is in the market for a bigger place to move into with his pregnant partner, Alice. They’ve saved up a big enough deposit to secure approval for a $750,000 home loan. However, Troy is aware that the longer you take to pay off your mortgage, the more it’ll cost overall. He uses the calculator to determine just how much he can save by shortening the loan term.
| Loan amount | Loan term | Interest rate | Fortnightly payment | Total interest |
|---|---|---|---|---|
| $750,000 | 30 years | 5.40% p.a. | $1,943.00 | $765,400 |
| $750,000 | 28 years | 5.40% p.a. | $2,000.00 | $705,366 |
| $750,000 | 25 years | 5.40% p.a. | $2,104.00 | $617,510 |
| Calculations are for illustrative purposes only and may not be reflective of the interest rate you’re offered on your home loan. Calculations do not include loan fees or any other home-buying costs. | ||||
Because the fortnightly payments on a 25-year loan are just out of their reach, Troy and Alice decide to negotiate a 28-year loan term instead. For less than $60 extra per fortnight, they’ll save upwards of $60,000 overall.
Example #3: Deciding how much to pay as a deposit
Inka is looking at buying her first unit, which would cost $450,000. She wants to keep some of her savings intact so she can furnish it, but is keen to know just how much that will impact the overall cost of the loan. She’s planning to make use of the Australian Government 5% Deposit Scheme, so she won’t have to pay lenders mortgage insurance (LMI).
The table below shows what different deposit sizes would mean for her home loan:
| Deposit | Loan amount | Loan term | Interest rate | Fortnightly payment | Total interest |
|---|---|---|---|---|---|
| $22,500 (5%) | $427,500 | 30 years | 5.50% p.a. | $1,120 | $445,905 |
| $33,750 (7.5%) | $416,250 | 30 years | 5.50% p.a. | $1,091 | $434,171 |
| $45,000 (10%) | $405,000 | 30 years | 5.50% p.a. | $1,061 | $422,436 |
| $56,250 (12.5%) | $393,750 | 30 years | 5.50% p.a. | $1,032 | $410,702 |
| Calculations are for illustrative purposes only and may not be reflective of the interest rate you’re offered on your home loan. Calculations do not include loan fees or any other home-buying costs. | |||||
Inka decides that paying a 10% deposit, rather than 5%, will leave her with enough money to comfortably furnish her home while still cutting down on her interest bill by over $20,000.
Home loan to income ratio
One key thing that lenders take into consideration when assessing your profile is how much of your income will be spent on your mortgage repayments. As a general rule, lenders won’t want to approve a loan whose repayments exceed 30% of your weekly or fortnightly payslip.
This is a greater factor for first-time buyers. If you already own a home and have been paying it off without issue, lenders are likely to be more lenient here. That doesn’t mean you’ll be automatically approved for your new home loan, though; if you’re deemed to be in mortgage stress, an application for a new home or a mortgage refinance could be rejected.
However, new limits on high debt-to-income (DTI) lending by Australian banks and other providers could impact your chances of home loan approval with a high DTI ratio. APRA announced in November 2025 that lenders could offer no more than 20% of their overall new lending to buyers with DTI ratios of six or more from 1 February 2026.
Tips for saving money on your home loan
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Put forward a larger deposit
As you can see, providing a larger deposit is a highly effective way to reduce the cost of your home loan. Increasing your deposit reduces your overall loan amount and therefore decreases the interest you’ll pay, potentially by a significant amount.
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Make additional repayments
Paying more than your minimum loan repayment can save a significant amount on your mortgage overall. This is particularly important if you opt for a variable rate home loan, as you can pay more when rates are at their lowest. On a $500,000 loan repaid monthly over 30 years at 5.35% p.a., paying just $200 extra per month would save you over $85,000 and clear your debt more than four years earlier.
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Use an offset account
An offset account is a type of bank account that offsets the sum of your home loan on a dollar-for-dollar basis, so the more you have in your offset account, the less interest you’ll pay on your home loan. This means that, in Example #3, Inka could alternatively pay the minimum deposit and store the rest of her funds in an offset, though this would mean her repayments would be higher.
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Compare as many options as you can
Do yourself a favour by comparing as many home loan options as possible. Adopt a proactive approach to your loan and don’t be shy about looking to refinance if it means you can save more (internal and external refinancing numbers were up by 29.1% and 18.7% across the September Quarter of 2025, respectively). When you apply through a mortgage broker, they can do the heavy lifting for you in this area.
