SUCCESS PROBABILITY
—%
Half of simulations maintain funding
Starting Annual Spending: $— (dynamically adjusted by guardrails)
How it’s calculated
After-cost compounding
We compound net of costs/withdrawals by year.
$$
PV_{t+1} \;=\; \big(PV_t - W_t\big)\,\times\,(1 + r_t)
$$
Portfolio percentile curves
For each year we take the 10th / 50th / 90th percentile of all simulated paths:
$$
P_q(y) \;=\; \operatorname{Quantile}_q\big(\{\,PV^{(i)}_y\,\}_{i=1}^N\big)
$$
Max drawdown
$$
\text{MDD} \;=\; \max_t \left(\frac{\operatorname{Peak}_t - PV_t}{\operatorname{Peak}_t}\right)
$$
Guaranteed income COLA (real)
$$
\text{real\_COLA} \;=\; \text{nominal\_COLA} - \text{CPI}
$$
Example with your last run (auto-filled):
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Retirement Portfolio Analysis
Guardrails Strategy: Tune Mode
Portfolio value over time
90th / 50th / 10th percentile
Portfolio Outcomes at Year 25
| Scenario | Probability | Final Wealth | Max Drawdown | Avg Annual Return |
|---|---|---|---|---|
| Poor (p10) | 90% chance of doing better | $0 | —% | —% |
| Median (p50) | 50% chance of doing better | $0 | —% | —% |
| Good (p90) | 10% chance of doing better | $0 | —% | —% |
Each line represents a different probability scenario based on 1000 simulations.
90th percentile is optimistic (~10% of runs do better), 50th is the median, 10th is cautious (~90% of runs do better).Tip: re-run the calculator, then come back and hit Refresh.
How to Read These Results
- The chart shows 3 possible paths for your portfolio.
- Guardrails will adjust your spending to help avoid running out.
- Even in the worst case (p10), guardrails prevented earlier depletion.
- Max drawdown shows the largest decline from any peak.
Key Insights
- —% success rate is below typical target of 80–90%.
- Consider reducing initial spending or adjusting allocation.
- High drawdowns indicate significant volatility risk.