Same returns, different order
Portfolio balance, end of each year
Year by year
Check the math (for the advisor who asks where these numbers come from)
This engine against the published research
Computed live from the data below every time this page loads, with fees set to zero so it lines up with how the original studies were run. If these rows ever stopped matching, the engine would be wrong.
Exactly what the engine does
- The withdrawal comes out at the start of the year; that year's return is applied to what's left. This is the Bengen and Trinity convention.
- Fees are charged on the balance once a year, after growth. The engine folds this into the return as (1 + r) × (1 − fee) − 1, which is arithmetically identical.
- The stock/bond mix is rebalanced every year at no cost.
- "Rising with inflation" applies the actual CPI-U for that calendar year in historical modes, not an assumed rate.
- A plan counts as failed the first year it cannot pay the full paycheck — the same test is applied to the protected-floor plan, so the comparison is like for like.
- The Flip reverses the return series. Reversing cannot change the arithmetic mean or the compound return, which is why those two tiles are identical for both portfolios — that is the proof, not a coincidence.
- Monte Carlo draws whole calendar years at random with replacement, taking stocks, bonds and inflation from the same year so their real correlation survives. It does not model that bad years cluster, so it is somewhat harsher than history in the tail.
Every number the tool runs on
Spot-check any row against Slickcharts, NYU Stern or the BLS. S&P 500 figures are total return with dividends reinvested.
Advisor notes — how to run this live (closed by default — keep it shut on a screen share)
This is an illustration, not a projection. Every figure on this page is a hypothetical calculation built from historical index returns. It is not a forecast, a guarantee, a recommendation, or a quote for any product. Past performance does not predict future results. Indexes are unmanaged and cannot be invested in directly. The fee you enter is deducted from the portfolio balance every year and every return shown is already net of it; the illustration still ignores taxes, trading costs, required minimum distributions and Social Security. Custom average-and-volatility mode draws each year independently from a normal distribution, which is a simplification — real markets cluster their bad years together, so a custom run is usually kinder than history. Withdrawals are taken at the start of each year and the portfolio is rebalanced annually. Guaranteed income in the Protected Floor mode is a generic modeling assumption, not any specific contract — real payout rates, fees, riders, surrender terms and the claims-paying ability of the issuing insurer will change the outcome. Anyone using this in front of a client is responsible for their own firm's suitability, supervision and disclosure requirements.
Data: S&P 500 annual total returns and CPI-U (December to December) 1928–2025; 10-year U.S. Treasury constant-maturity total return, Damodaran/NYU Stern. Verified against Slickcharts, Wikipedia, BLS and NYU Stern.