Best Rent vs Buy Calculators in Australia (2026) Updated March 2026
The question of whether to rent or buy is one of the most consequential financial decisions Australians make. It involves property prices, interest rates, stamp duty, investment returns, and a time horizon that stretches over decades. You'd think the tools available to help make this decision would be rigorous and transparent.
Many aren't.
We reviewed the four most commonly referenced Australian rent vs buy calculators — Domain, Canstar, realestate.com.au, and SmartKoala — against a set of objective criteria: data sources, methodology transparency, input flexibility, and whether the model accurately accounts for what each path actually costs.
Here's what we found.
The Criteria
A credible rent vs buy calculator should:
- Use real, cited property growth data — not an undisclosed assumption or a national average applied to all cities
- Model the renter's investment returns transparently — accounting for tax on interest, and different savings strategies
- Include stamp duty — one of Australia's largest property transaction costs, often $20,000–$70,000
- Show year-by-year outcomes, not just a single end-point figure
- Document its methodology so users can verify the maths
- Be free from product promotion — no mortgage product recommendations embedded in the result
Comparison Table
| Feature | SmartKoala | Domain | Canstar | realestate.com.au |
|---|---|---|---|---|
| City-specific property growth data | Yes (CBA + Westpac) | National average | ~ Generic estimate | Not stated |
| Data source documented on page | Named banks, dated | Not disclosed | ~ Partial | No |
| Stamp duty modelled | Optional input | No | ~ Estimate only | No |
| Tax on savings interest | User-selectable tax bracket | No | No | No |
| Multiple renter savings strategies | Match mortgage or save difference | No | No | No |
| Year-by-year wealth breakdown | Table + chart | No | ~ Chart only | No |
| Break-even year shown | Yes | No | ~ Approximate | No |
| Cash flow comparison (monthly) | Yes | No | No | No |
| Methodology documented | Full explainer on page | No | ~ Brief notes | No |
| Free, no sign-up required | Yes | Yes | Yes | Yes |
| Affiliate / product promotion in results | None | ~ Subtle | Yes (mortgage products) | Yes (listings) |
Tool-by-Tool Analysis
SmartKoala — smartkoala.app/rent-vs-buy/
What it does well: SmartKoala's calculator is built specifically around the Australian market. City-specific property growth forecasts are sourced from CBA Economics and Westpac Economics publications — named, dated, and explained in the methodology section below the calculator. When the two banks diverge significantly (as they do on Melbourne's 2027 forecast — CBA +3% vs Westpac +6%), the calculator averages both and documents this explicitly.
Crucially, the tool models the renter's scenario properly. It lets you choose whether the renter saves the cash flow difference (realistic lifestyle scenario) or matches the buyer's full mortgage payment (true apples-to-apples financial comparison). Interest on the renter's savings is taxed at a user-selected marginal rate. Stamp duty can be entered and is added to the renter's initial savings, correctly representing the upfront cost buyers pay that renters avoid.
The result shows monthly cash flow, net wealth for both paths at the selected timeframe, year-by-year wealth table, an interactive chart, and the break-even year. Methodology is fully documented on the same page — no need to hunt for a separate FAQ or help article.
What it doesn't include: Ongoing ownership costs (maintenance, council rates, insurance) and buying/selling transaction costs (~5–6% of price). The documentation notes these exclusions and explains they would push the break-even point out by 2–5 years. No product promotion in results.
Domain — domain.com.au
What it does well: Domain's calculator is straightforward and loads quickly. It covers the basics — purchase price, deposit, interest rate, rental cost — and outputs a comparison figure.
What it lacks: No disclosure of property growth rate assumptions or data sources. No stamp duty modelling. No tax on savings interest. No year-by-year breakdown or chart. The result is a single number at a single point in time, which makes it difficult to understand sensitivity to assumptions. Domain's business is selling property — their interest is in buyers, not renters.
Canstar — canstar.com.au
What it does well: Canstar is a well-known comparison site and their calculator includes more inputs than Domain. It outputs a chart showing the two paths over time, which is useful.
What it lacks: Results are framed to lead into mortgage product comparisons — Canstar earns referral fees from lenders it compares, which creates an implicit conflict of interest. Property growth rate assumptions are not clearly disclosed. Stamp duty is estimated (not entered by the user). Tax on investment returns is not modelled. There's no documented methodology on the page.
realestate.com.au — realestate.com.au
What it does well: Australia's largest property listings site offers a basic comparison tool accessible from property listing pages, which is contextually useful when you're looking at a specific property.
What it lacks: Minimal inputs, no data source disclosure, no stamp duty, no tax modelling, no year-by-year output. The result is essentially a prompt to search for properties on the platform. Not a genuine financial modelling tool.
Why Data Sources and Methodology Matter
The output of a rent vs buy calculator is only as reliable as the assumptions feeding it. Property growth rate is the single most sensitive variable — a 1% difference in annual growth over 10 years has a massive effect on the outcome. A calculator that uses an undisclosed, static growth rate is essentially guessing.
Australian property markets are deeply local. Sydney and Melbourne have very different growth trajectories to Perth, Brisbane, and Adelaide — and often diverge significantly even within a city (inner vs outer suburbs, houses vs apartments). A national average growth rate applied uniformly produces results that are accurate for nowhere in particular.
The same applies to the renter's scenario. If the calculator assumes savings earn 3% gross without applying the investor's marginal tax rate, it overstates the renter's returns — particularly for higher-income earners in the 37%+ bracket, where a 5% gross rate becomes 3.15% after tax.
These details compound over 10 years. The difference between a rigorous and a simplified calculation can be $80,000–$120,000 in modelled net wealth — enough to flip the conclusion.