The Best Mortgage and Finance Calculators in Australia

This Is Fintech provides general information only. This is not financial advice. Always consider your personal circumstances and speak with a licensed professional before making financial decisions.

Online calculators are one of the genuinely useful things the internet has produced for personal finance. The right calculator turns an abstract decision — “should I fix my rate?” or “how much can I actually borrow?” — into concrete numbers you can work with. Here are the ones worth bookmarking.

Home Loan Calculators

MoneySmart Mortgage Calculator (ASIC)

ASIC’s MoneySmart calculators are the most trustworthy in Australia because they’re not trying to sell you anything. The mortgage repayment calculator is straightforward: enter loan amount, interest rate, and term, and it shows you monthly repayments and total interest paid. The comparison tool lets you model two different rates side by side.

Best for: Understanding what a rate change actually costs you in dollar terms. If your lender offers a rate 0.3% lower, this shows you the real saving over 25 years.

URL: moneysmart.gov.au/tools-and-resources/calculators-and-apps/mortgage-calculator

Canstar’s Borrowing Power Calculator

Canstar’s borrowing power calculator is the most realistic of the major comparison sites. It accounts for expenses, existing debts, and dependants — not just income. The result gives you a serviceable estimate of what a lender would approve, rather than the theoretical maximum.

Best for: Getting a realistic borrowing figure before you start talking to lenders or brokers.

Finder’s Home Loan Repayment Calculator

Finder’s calculator is the most feature-rich for modelling scenarios. You can add extra repayments, see an amortisation schedule month by month, and model offset account impact. Useful for working out how much time you’d save by adding $500/month to your repayments.

Best for: People already in a mortgage who want to model overpayment scenarios.

Refinancing Calculators

InfoChoice Refinance Calculator

InfoChoice’s refinancing calculator is the most honest about the break-even point — it factors in exit fees, application fees, and the time it takes to recoup switching costs. A lot of refinancing calculators show you the rate saving without showing you what it costs to switch, which can make a marginal decision look better than it is.

Best for: Working out whether refinancing is actually worth it once you factor in all the costs.

Superannuation Calculators

ASIC MoneySmart Superannuation Calculator

The super calculator on MoneySmart models projected retirement balance based on current balance, salary, employer contributions, and assumed investment return. It’s not precise — the return assumptions are estimates — but it’s useful for understanding the long-term impact of salary sacrifice contributions.

Best for: Modelling the difference between 10% and 15% super contributions over 20 years.

Tax and Income Calculators

ATO Tax Withheld Calculator

The ATO’s own calculator gives you the most accurate take-home pay figure because it uses the actual tax tables. Useful when you’re evaluating a job offer or working out what a salary sacrifice arrangement will do to your take-home.

Best for: Exact take-home pay calculations, tax withheld on additional income, salary sacrifice impact.

What to Be Careful About

Bank-provided calculators have a conflict of interest — they’re designed to make the bank’s own products look favourable. Use them as a starting point, then verify with ASIC’s tools.

Rate assumptions: Any calculator projecting outcomes over 10+ years is using assumed interest rates. A 0.5% difference in the assumed rate produces dramatically different end results. Always run best-case and worst-case scenarios, not just the default.

Fees omitted: Many calculators show repayments but exclude ongoing fees, offset account costs, or lenders mortgage insurance. Make sure you’re comparing total cost, not just the rate.

The calculators above are the ones that are upfront about their assumptions and don’t have an obvious product to sell you.