Hebeler Autopilot II Calculator
Three-quarters of last year’s spending blended with a fresh amortised withdrawal off the current balance.
Part of the FIRE simulator, a historical backtest calculator that replays your plan across every rolling window of market history since 1871.
How the Hebeler Autopilot II strategy works
The Autopilot II variant of Henry Hebeler’s method takes a weighted blend: by default 75% of last year’s spending and 25% of a fresh amortised (annuity-style) withdrawal off the current balance. Anchoring most of each year’s withdrawal on last year’s keeps income smooth while still letting the portfolio nudge spending up or down over time.
What the Hebeler Autopilot II strategy trades off
Anchoring three-quarters of each year's withdrawal on last year's spending produces smooth income that still drifts, slowly and automatically, toward what the portfolio can support. That anchor delays every adjustment, after a crash and after a recovery alike.
Pros and cons
Pros
- Smooth, stable year-to-year income
- Still tracks the portfolio over the long run
- Automatic, rules-based adjustment
Cons
- Adapts slowly to sudden market moves
- Can lag a sharp portfolio recovery
- Blend weight and return assumption both matter
Parameters you can adjust
- Prior-spend weight (share of last year): How much of each year’s withdrawal is anchored to last year’s spending versus a fresh amortized amount. Higher (closer to 1) makes income smoother.
- Assumed annual return: The yearly return the amortized (annuity-style) part of the blend assumes when spreading the balance over the remaining years.
Backtest Hebeler Autopilot II against market history
Opens the simulator with Hebeler Autopilot II already selected, so you only set your portfolio and horizon.