11 Free Mortgage Calculators Every Australian Home Buyer Should Use

Buying property in Australia involves a sequence of numbers most people work out one at a time, usually under time pressure: what can I borrow, what will it actually cost to settle, what will repayments look like, and — years later — is it worth refinancing? This guide groups the calculators that answer each question by the stage of the journey they belong to, so you can jump straight to the one you need right now.

Every calculator below is free, runs entirely in your browser, and needs no sign-up to get a result.

Stage 1: Work out what you can afford

Before you look at a single property, these two answer "what's actually realistic for me?"

Borrowing Capacity Calculator

When to use it: you haven't started looking yet and want to know your ceiling. It applies the same income-minus-expenses-minus-debts-minus-buffered-repayment logic every Australian lender uses, so you get a realistic maximum loan rather than a marketing number.

→ Try the borrowing capacity calculator · full worked-example guide

Purchasing Power Calculator

When to use it: you already know your deposit and borrowing capacity and want a single number — the maximum property price you can actually offer on, once stamp duty and other settlement costs are accounted for.

→ Try the purchasing power calculator

Stage 2: Work out the real cost of buying

A purchase price is never the full number. These two catch the costs that surprise people at settlement.

Stamp Duty Calculator

When to use it: as soon as you have a property price and a state in mind. Stamp duty rules and first home buyer concessions differ across every Australian state and territory, and the gap between "aware of stamp duty" and "know the exact figure for my state" is often tens of thousands of dollars.

→ Try the stamp duty calculator

Property Buying Cost Calculator

When to use it: when you want the full settlement bill, not just stamp duty — conveyancing, building and pest inspections, lender fees, and LMI (if applicable) all add up before you get the keys.

→ Try the property buying cost calculator · full worked-example guide

Stage 3: Choose and compare the loan itself

Once you have a property and a lender shortlist, these decide what the loan actually costs you.

Loan Repayment Calculator

When to use it: the workhorse calculator — weekly, fortnightly, or monthly repayments, principal & interest vs interest-only, and how offset or extra repayments change the picture. This is the one most people reach for first.

→ Try the loan repayment calculator · how loan interest is actually calculated

LVR Calculator

When to use it: to see exactly where your deposit places you against the 80%, 90%, and 95% loan-to-value thresholds — because your LVR band is what determines whether LMI applies, and roughly how much.

→ Try the LVR calculator

LMI Calculator

When to use it: if your deposit is below 20%. LMI can add tens of thousands of dollars to your upfront cost (or your loan balance, if capitalised) — model it before you commit to a purchase price, not after.

→ Try the LMI calculator · full guide: what LMI actually costs

Stage 4: Get ahead once you have the loan

The loan is settled — now the question shifts to paying less interest over time.

Offset Calculator

When to use it: to see how much a linked transaction account balance saves in interest, while keeping the money fully accessible. On a $500,000 loan, a constant $50,000 offset balance can save well over $190,000 in interest over the life of the loan.

→ Try the offset calculator · full guide: how offset accounts work

Extra Repayment Calculator

When to use it: to see what even a modest top-up above your minimum repayment does over time. An extra $500 a month on a typical loan can pay it off nine years early.

→ Try the extra repayment calculator · full guide with worked examples

Stage 5: Already have a loan — refinance or tap equity

Years into a loan, the questions change again: is my current deal still competitive, and what can I do with the equity I've built?

Refinance Calculator

When to use it: to compare your current loan against a new offer, side by side — potential savings on rate and repayments, weighed against any switching costs.

→ Try the refinance calculator · full worked-example guide

Home Equity Calculator

When to use it: to see your usable equity for a renovation, an investment property deposit, or debt consolidation — calculated against the 80/90/95% LVR caps lenders actually apply, not just your raw equity on paper.

→ Try the home equity calculator

If you're investing rather than owner-occupying

Everything above applies whether you're buying to live in or buying to rent out, but investors have one extra layer: the tax position. If you're weighing an investment property, model the after-tax cash flow with the negative gearing calculator — the 2026 policy-change guide covers what's changed and what it means for holding vs selling decisions.

Frequently asked questions

Are these mortgage calculators actually free to use?

Yes — every calculator linked above is free, with no sign-up required to get a result.

How accurate are online mortgage calculators?

The maths is exact; what varies is lender-specific policy (income shading, HEM tiers, the exact rate offered). Use calculator output as a reliable indicative figure, then confirm specifics with a lender or broker.

Do I need to know which calculator to use first?

Start with borrowing capacity (or purchasing power if you already know your deposit) before you've picked a property. Move to stamp duty and buying costs once you have a price in mind, then to repayments, offset, and extra repayments once the loan is settled.

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This article provides general information current at July 2026 and does not constitute personal financial advice. Speak to a licensed mortgage broker or your lender before making property or borrowing decisions.