Projection start point
SimulationThe numbers shown come from a sample profile for illustration – in the calculator you see your own values.
The dropdown lets you choose from which FIRE phase the Monte Carlo simulation (the green corridor in the chart) should start. The expected trajectory and the y-axis always stay the same – only the probability corridor "moves" forward.
Background: over 50+ years the corridor inevitably becomes very wide – in old age almost anything is possible (from broke to multimillionaire). Not very helpful. By setting the start point to e.g. "Withdrawal", you answer a more targeted question: "How robust is my 4% rule over the next 30 years?"
Start points are only offered if the respective phase is enabled (Coast/Barista) and lies in the future.
How it is calculated
Starting wealth = value of the expected trajectory at the phase age (real return, without volatility)
Savings rate = only relevant in the accumulation phase – from Coast/Barista/withdrawal onwards there is no more saving
Withdrawals from the chosen start: Barista withdrawal → full withdrawal → remaining need in the pension phase (taken from your retirement configuration)
1,000 simulation runs · volatility σ is calculated from your allocation (see glossary) · Box-Muller normally distributed returns around the real return
Example: with a real return of 3% and σ = 12%, ~68% of annual returns lie between −9% and +15% (±1σ), ~95% between −21% and +27% (±2σ)
Display: corridor between the 10th and 90th percentile (outer) and the 25th and 75th percentile (inner)
Good to know
Volatility from your portfolio:The range of fluctuation (σ) is calculated automatically from your allocation — see the glossary entry "Volatility". Conservative portfolios → narrower corridor, aggressive → wider.
Assumption:When you switch to a later phase, the simulation assumes your wealth at the start of that phase exactly matches the expected trajectory. In reality it will of course differ – so use the selection as a what-if tool, not as a forecast.
Drive by sight instead of planning for the worst case:The inner corridor (25–75%) shows the likely trajectory – that is your realistic expectation. The outer edge (10/90%) shows the best- and worst-case scenarios. Always optimizing for the 10th percentile may mean working longer than necessary. It can often make more sense to start FIRE when the prospects of success are good and to steer if things go less well (reduce withdrawals, add a Barista phase, readjust later).
Success rate depends on the start point:The success probability above only evaluates paths from the selected start point. If you switch to "Withdrawal", you see specifically how robust your withdrawal phase is – fluctuations during accumulation no longer count.