Calculate your financial independence number, years to FIRE, and safe withdrawal rate with lean/fat FIRE scenarios.
Retirement readiness is framed here as a portfolio target rather than a conventional retirement age. Enter current investments, ongoing savings, expected retirement spending, and planning assumptions to estimate a FIRE number and how long the modeled portfolio takes to reach it. Lean and fat spending cases show how different lifestyles change the target. The common mistake is treating the withdrawal rate as an investment return. It instead connects planned retirement spending to the required portfolio, while growth assumptions separately affect the years-to-FIRE estimate.
For each spending case, the portfolio target is annual retirement spending divided by the withdrawal rate expressed as a decimal. A 4 percent planning rate therefore corresponds mathematically to 25 times annual spending, while a lower rate requires a larger balance. Lean and fat FIRE represent different spending assumptions, not different types of investments or retirement accounts.
The years-to-FIRE result compares the target with the modeled path of invested assets. Current investments, recurring additions, and assumed growth determine that path, with the estimate ending when the projected balance reaches the target. Changing retirement spending moves the finish line, while changing contributions or expected return changes how quickly the modeled portfolio approaches it.
No. The withdrawal rate converts a retirement spending amount into a target portfolio and describes the planned withdrawal relative to that portfolio. Expected investment return is a separate assumption used to project growth. Treating the two percentages as interchangeable can materially understate the required balance or shorten the displayed timeline.
No. It means the modeled balance has reached the modeled target under the supplied assumptions. Retirement feasibility also depends on taxes, account access, health costs, lifespan, market volatility, and changes in spending. Treat the result as a scenario checkpoint, and test less favorable returns and higher expenses before relying on one projected date.
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