The nine rules
| Rule | What it does | Flexibility | Can it ruin? | Calculator |
|---|---|---|---|---|
| Fixed real dollar | Year-one withdrawal is a percentage of the starting portfolio; later years raise that dollar amount with inflation and never re-read the balance. | None after year one | Yes | Open |
| Fixed percentage | Each year withdraw a constant percentage of whatever the portfolio is now. Income floats; the portfolio cannot be exhausted by the rule itself. | Smooth each year | No — income floats | Open |
| Guyton-Klinger | Inflation raises unless a losing year left the rate above the start; cut or raise about 10% when the current withdrawal rate leaves a band around the initial rate, with no cuts in the last 15 years. | Discrete cuts / raises | Yes | Open |
| Vanguard dynamic spending | A target percentage of the current balance, clamped so the real change versus last year cannot exceed a ceiling or a floor. | Smooth each year | Yes | Open |
| Endowment / Yale smoothing | Most of last year’s inflation-indexed spend, plus a slice of a target percentage of current market value. | Smooth each year | Yes | Open |
| VPW / variable percentage | Each year spend the remaining-horizon annuity of the current balance at an assumed real return. | Smooth each year | No — income floats | Open |
| CAPE-based withdrawal | Set the first-year rate from today’s CAPE earnings yield, then inflate that dollar amount like a fixed-real rule. | None after year one | Yes | Open |
| Risk-based guardrails | Cut or raise when remaining probability of success leaves a chosen band, rather than when the withdrawal rate does. | Discrete cuts / raises | Yes | Open |
| Merton dynamic | Merton’s risky share from risk aversion and volatility; spending is the remaining-horizon annuity at the implied return. | Smooth each year | No — income floats | Open |
A withdrawal strategy is a rule for next year's spending given this year's portfolio. The 4% rule is one such rule. The other eight answer the same question with a different feedback loop. This page is the comparison table; each named rule has its own calculator in the last column.
How to choose
If you want a single number and a sanity check, start with safe withdrawal rate or the rule of 25. If you want spending that reacts to markets, Guyton-Klinger and Vanguard dynamic are the two that show up in the planning literature. If you want to spend the balance over a known horizon, VPW or Merton. If you want valuations to set year one, CAPE. If you want the rails to trip on remaining odds rather than on the current withdrawal rate, risk-based rails. To pick between the two kinds of rails, see which retirement guardrails fit.
The 4% rule vs guardrails page is the comparison most people actually mean. The endowment rule is explained, with a worked example, in the Yale spending rule guide. The methodology page is how Killion runs the same rules on 1,000 seeded paths.
A spending rule is only half of a drawdown plan. Which accounts you draw from first, required minimum distributions, when you claim Social Security and whether you keep a cash bucket all change how long the money lasts. The guide to retirement withdrawal and drawdown strategies shows how those pieces fit together.
The 1,000-path version
Every calculator on this hub can show a deterministic line. Several also run a 1,000-path band. The product demo runs the same engine on a fictional household with no signup: open the live demo.