Returns and inflation vary widely by country, currency, and time period — the starting numbers are neutral placeholders, not a prediction. Replace them with your own expectations.
At a 4% withdrawal rate, covering $45,000 of annual expenses would need about $1,125,000 invested if that spending never changed. Allowing for the spending smile across ages 50–95, the figure comes down to about $1,020,000. At your current savings and a 3.9% real return, that is roughly 20 years away.
The classic "25× your expenses" rule assumes you spend the same amount every year for the rest of your life. Real retiree spending tends to run high through the active early years, ease through the seventies, then lift again later as care costs arrive — the spending smile. Both numbers are shown because the 25× figure is what the term FIRE usually means to a reader, while the smile-adjusted one is what OptiAI models in the app.
Educational estimate, not financial advice. The 4% rule is a guideline, not a guarantee, and every figure here is conditional on the assumptions you entered — if they hold. The timeline grows your savings at the real (inflation-adjusted) return, so it is in today's money; it does not model taxes, sequence-of-returns risk, or a safety margin.
How it works
The classic FIRE number is your annual expenses divided by your withdrawal rate — the familiar "25× your expenses" at a 4% rate. The timeline grows your current investments plus annual savings until you reach it. Lowering expenses pulls the number down and the date closer.
Two numbers, and why
The 25× calculation assumes you spend the same amount, in today's money, every year for the rest of your life. Studies of what retirees actually spend find a different shape: high through the active early years, easing through the seventies, then lifting again at the end as care costs arrive — the spending smile. Modelling that shape generally gives a somewhat smaller number.
Both are shown. The classic figure is what the term FIRE means to most readers and dropping it would be its own kind of dishonesty; the smile-adjusted figure is the one OptiAI models in the app, so the number you see here is the number you will see there for the same inputs.
The timeline is in today's money
Your FIRE number is expressed in today's purchasing power, so the growth applied to reach it uses the real (inflation-adjusted) return rather than the nominal one — combined with the Fisher formula, r = (1+nominal)/(1+inflation) − 1, rather than the simpler nominal − inflation shortcut. Growing at a nominal rate toward a today's-money target compares two different currencies and pulls the date forward for free.
How OptiAI helps
OptiAI connects your FIRE target to your real net worth and spending picture, so your independence timeline updates as your life does — not just when you remember to recalculate.