Withdrawal Strategy Simulator
Stress-test your retirement portfolio with 1,000 Monte Carlo simulations. See success rates, percentile outcomes, and compare withdrawal strategies side-by-side.
Simulation Results
Success Rate
68.8%
688 of 1,000 simulations: money lasted 30 years
10th Percentile
$0
Worst ~10% of outcomes
Median
$1,050,639
Typical outcome
90th Percentile
$8,232,040
Best ~10% of outcomes
Portfolio Value by Percentile
Bands show the range of outcomes across 1,000 simulations. Strategy: Fixed (4% Rule).
Strategy Comparison
All three strategies run with the same starting portfolio and withdrawal amount.
Fixed (4% Rule)
Current70.6%
success
Variable Percentage
100.0%
success
Guardrails
100.0%
success
Historical Context
The Trinity Study (1998, updated 2011) found that a 4% withdrawal rate from a 50/50 stock-bond portfolio had a 95%+ success rate over 30-year periods using US historical data from 1925–2009.
For FIRE with longer time horizons (40–60 years), many researchers recommend a 3–3.5% withdrawal rate to account for the longer sequence-of-returns risk.
Variable strategies like Guardrails and Variable Percentage Withdrawal tend to outperform fixed strategies in Monte Carlo simulations because they reduce spending during poor market conditions — at the cost of income predictability.
Frequently Asked Questions
What is a Monte Carlo simulation?
It runs your withdrawal plan through thousands of random market scenarios (based on historical return distributions) to estimate the probability your money lasts through retirement.
What success rate should I target?
Most financial planners suggest 90–95%. Below 80% means significant risk of running out of money. Above 95% may mean you're being too conservative and could enjoy more of your wealth.
Which withdrawal strategy is best?
There is no single best strategy. Fixed withdrawal (4% rule) is simplest. Variable strategies like guardrails adapt to market conditions and generally have higher success rates but less predictable income.
Methodology
Monte Carlo Method: We run 1,000 independent simulations. Each year in each simulation draws a random annual return from a normal distribution with the specified mean and ~15% standard deviation (consistent with long-term US equity volatility).
Random Number Generation: Uses the Box-Muller transform to generate normally-distributed random numbers in the browser.
Success Definition: A simulation "succeeds" if the portfolio balance remains above zero at the end of the simulation period.
Guardrails Strategy: Based on the Guyton-Klinger guardrails. Withdrawals are raised 10% when the current withdrawal rate falls below 80% of the initial rate, and cut 10% when it exceeds 120%.
Limitations: This is a simplified model. It does not account for taxes, fees, Social Security, part-time income, or behavioral changes. Results vary due to randomness; run again to see a different set of outcomes.
Financial Disclaimer: This simulator is for educational and informational purposes only. Monte Carlo simulations are probabilistic models with significant limitations. Past market behavior does not guarantee future results. This does not constitute financial, investment, tax, or legal advice. Please consult a qualified financial professional (CFP or RIA) before making retirement planning decisions. Full disclaimer.