Buying a home is one of the biggest financial decisions most Australians make.
Before signing up for a loan, it helps to know what your repayments will look like — and how small tweaks can make a big difference over time.
That’s where a mortgage repayment calculator comes in. It lets you estimate your repayments, total interest, and potential savings from extra payments — all before you apply.
Table of contents
- What you’ll need
- Step-by-step guide
- Understanding your results
- Common mistakes to avoid
- Smart ways to save
- The bottom line
What you’ll need
To get started, gather a few key details:
- Loan amount – for example, $650,000
- Interest rate – fixed or variable
- Loan term – typically 25–30 years
- Repayment frequency – weekly, fortnightly, or monthly
- Optional: extra repayments or an offset balance
These inputs form the basis for your loan projection.
Step-by-step guide
- Open the Mortgage Calculator.
- Enter your loan amount, interest rate, and term.
- Choose between principal & interest or interest-only.
- Switch repayment frequency to compare how totals change.
- Add extra repayments to see how much time and interest you can save.
Tip: Paying fortnightly can effectively add one extra month’s worth of repayments each year, helping you pay off the loan faster — without feeling the difference.
Understanding your results
The calculator shows more than just your repayment amount. You’ll see:
- Repayment amount – what you’ll pay each period
- Total interest – how much you’ll pay over the life of the loan
- Loan end date – when you’ll be mortgage-free
- Amortisation schedule – how much of each payment goes to principal vs interest
This breakdown helps you see where your money goes — and how even small extra repayments can save thousands.
Common mistakes to avoid
A calculator gives estimates, not approvals. Avoid these common pitfalls:
- Forgetting to include fees or Lenders Mortgage Insurance (LMI)
- Comparing fixed vs variable without checking break costs
- Assuming an introductory rate lasts for the entire term
Smart ways to save
Once you understand your baseline, try running a few scenarios:
- Add $50 extra per week to see how quickly the term shortens
- Reduce the loan term for faster equity growth
- Use an offset account to lower interest without locking away savings
- Model a 0.50% rate rise to test your budget resilience
Even small changes — like rounding repayments up to the nearest $10 — can shave years off your mortgage.
The bottom line
A mortgage calculator won’t replace financial advice, but it’s an excellent way to take control.
It helps you plan, test scenarios, and prepare for different interest rate environments before meeting with a lender or broker.
Ready to run the numbers?
Try the Mortgage Calculator and see how adjusting your repayments, frequency, or extra payments could save you thousands over the life of your loan.