Compare future pathways
Set a baseline from your current numbers, then create alternative scenarios by changing income, expenses, returns or life events like a career break. The calculator projects each one side by side and shows how many years earlier or later each reaches financial independence, so you can see which decisions actually move the needle.
Set your baseline scenario with your current income, savings rate, and balances. Then create an alternative scenario with the changed assumption — lower income, higher expenses, a lump sum cost. The calculator shows you your FIRE date in each scenario and the exact difference.
The delta panel highlights which inputs changed and by how much, so you can see exactly what's driving the difference in outcomes. Use this to evaluate major decisions before committing to them.
A scenario comparison calculator lets you model how a specific life decision — taking a career break, buying a bigger house, having a child — changes your financial independence date. You set a baseline, apply the change, and see the exact difference in years and dollars.
A one-year career break typically pushes your FIRE date out by 1.5–3 years, not just one. The reason: you lose not just the year's savings, but the compounding those savings would have generated. A career break at 35 on a $500k portfolio at 8% returns costs roughly $40k in forgone growth plus the year's savings — often $60–80k total in future portfolio value.
A larger mortgage increases monthly expenses, which raises your FIRE number (the portfolio required to sustain your lifestyle). A $200k larger mortgage at 6.5% adds roughly $1,300/month to repayments. That additional expense requires an extra $400k–$500k in your independence portfolio, assuming a 4% withdrawal rate.
Australian government data suggests raising a child to 18 costs $250,000–$450,000. For FIRE planning, the relevant number is the annual cost during the accumulation phase — typically $15,000–$25,000/year during school age, including childcare, education, activities. This reduces your annual surplus and extends your FIRE timeline by 3–7 years depending on income.
Compare the guaranteed return of paying off debt (equal to your interest rate) versus the expected investment return. If your mortgage is 6.5% and you expect 8–9% from ETFs, investing appears better — but ETF returns aren't guaranteed. Risk-averse investors often prefer the certainty of debt payoff. Most financial planners suggest a blend: maintain a meaningful offset while continuing to invest.
A higher income increases your annual surplus, which compounds faster than a proportional salary increase. Going from $80k to $100k income doesn't just add $20k — after tax it adds roughly $13k/year net, which invested at 8% adds around $190k to your portfolio over 10 years. The scenario calculator shows the FIRE date change from income growth directly.
These sometimes conflict. Strategies that maximise wealth (e.g., maximising salary sacrifice into super) can delay accessible portfolio growth, pushing out the date when you can actually stop working. Most people benefit from optimising for the earliest date they could stop mandatory work — then continuing to accumulate if they want.
I'm a geologist-turned-builder who got frustrated with financial calculators that hand-wave how Australian tax actually works.
Every projection on MyNextDollar runs on current ATO mechanics for FY2026-27 — Stage-3 brackets, super contribution caps and HELP thresholds.
The calculation engine is covered by 88 unit tests and 10,000 fuzz scenarios, so what you see is exactly what the rules produce — not a rough estimate.