Australian FIRE Calculator Assumptions

The FIRE app is designed for comparison, not prediction. It gives you a consistent ETF vs property frame so you can test the same savings rate, horizon, and tax settings under different assumptions.

What the tool is actually modelling

The core comparison engine models an ETF path and an investment property path using Australian resident tax settings, annual contributions, property cashflow inputs, and a FIRE target derived from spending plus safe withdrawal rate.

Return and growth assumptions

ETF total return and property growth are nominal assumptions. They should represent a long-run expectation that is suitable for a scenario comparison, not a one-year forecast or a claim about what markets must do next.

Tax treatment and simplification

The model applies Australian resident individual tax brackets, a simplified Medicare levy, and optional CGT discount treatment where relevant. It is useful for comparing directions and tradeoffs, but it is still a simplification rather than a full tax or advice workflow.

Property cashflow inputs

Rental yield, vacancy, management fees, maintenance, annual expenses, loan costs, and sell year are explicit. These inputs can change the property path materially, so this page should help users test ranges rather than defend one precise number.

FIRE target logic

FIRE target is derived from annual spending and safe withdrawal rate. If spending or SWR changes, your target and FIRE timing change automatically, which is why the app should be read as a moving scenario model rather than a fixed answer.

What to test next

Start with a clean baseline, then change one major lever at a time. Good first tests are: lower ETF return, higher vacancy, higher maintenance, or a later property sale year. Save each variation as a separate scenario so the comparison board stays interpretable.

If you landed here from a broad search like "FIRE calculator Australia", do not try to optimise every assumption before you run the tool. Set a realistic baseline first, then use this page to decide which assumptions deserve a separate downside scenario.

Open the FIRE calculator →