Free Tool
How Long Does Your Money Last?
A withdrawal rate calculator built for people who've already won the accumulation game. Three inputs get you started. Expand for Monte Carlo simulation, Guyton-Klinger guardrails, and account-level modeling.
Withdrawal Rate Calculator
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Methodology
Not just the 4% rule.
Deterministic projection
Your portfolio is projected year by year using your real return, inflation, Social Security start age, and spending growth. This gives you a baseline: does the math work assuming average returns?
Monte Carlo simulation
1,000 independent simulations sample returns from historical distributions calibrated to your asset allocation. The result: a success probability and confidence bands that account for sequence-of-returns risk — the thing that actually kills portfolios.
Variable spending (optional)
Guyton-Klinger guardrails adjust your spending based on portfolio performance. If your withdrawal rate exceeds 120% of your initial rate, spending drops 10%. If it falls below 80%, spending rises 10%. This flexibility dramatically improves survival rates.
Account sequencing (optional)
Break down your portfolio by tax treatment — taxable, tax-deferred, and Roth. The calculator models conventional withdrawal ordering and shows when each account depletes. Add Roth conversions to see the impact on your terminal value.
Return assumptions
| Allocation | Real Mean | Std Dev |
|---|---|---|
| 80/20 Aggressive | 6.2% | 14.0% |
| 70/30 | 5.8% | 12.3% |
| 60/40 Balanced | 5.3% | 10.5% |
| 50/50 | 4.8% | 8.8% |
| 40/60 Conservative | 4.3% | 7.0% |
Source: Historical S&P 500 + US Aggregate Bond returns 1926-2024, inflation-adjusted.
Known simplifications
- Single real return rate per year (no intra-year volatility)
- Tax rate applied as flat effective rate, not bracket-based
- Social Security treated as fixed real dollar amount
- Inflation modeled as constant, not stochastic
- No modeling of healthcare cost shocks or long-term care
Common Questions
Withdrawal rates, demystified.
- What is a safe withdrawal rate for early retirees?
- The traditional 4% rule was designed for 30-year retirements starting at 65. For early retirees with 40–60 year horizons, most research suggests a lower rate of 3.0–3.5% provides more safety margin. However, this depends heavily on asset allocation, spending flexibility, and other income sources like Social Security. The calculator above models your specific situation with Monte Carlo simulation rather than relying on a single rule of thumb.
- How does the Monte Carlo simulation work?
- The calculator runs 1,000 independent simulations of your retirement. Each simulation samples annual returns from a log-normal distribution calibrated to historical stock/bond data for your chosen asset allocation. The result is a success probability (percentage of simulations where your money lasts through your life expectancy) and confidence bands showing the range of outcomes. This is more realistic than a single deterministic projection because it accounts for the randomness of market returns and sequence-of-returns risk.
- What are Guyton-Klinger guardrails?
- Guyton-Klinger is a variable spending strategy that adjusts your withdrawals based on portfolio performance. If your current withdrawal rate exceeds 120% of your initial rate (the ceiling), you reduce spending by 10%. If it drops below 80% of your initial rate (the floor), you increase spending by 10%. This flexibility significantly improves portfolio survival rates compared to rigid inflation-adjusted withdrawals, while keeping spending within a predictable range. Enable it in the Advanced Modeling section to see the impact.
- How does the withdrawal sequencing work for different account types?
- The calculator follows the conventional tax-efficient withdrawal order: taxable brokerage accounts first (benefiting from lower capital gains rates), then tax-deferred accounts like 401(k)s and Traditional IRAs (taxed as ordinary income), and Roth accounts last (tax-free growth is most valuable to preserve). If you've specified Roth conversions, those are modeled as annual transfers from tax-deferred to Roth during the specified age range. Enter your account balances in the Advanced Modeling section to see when each account depletes.
- What return assumptions does the calculator use?
- Returns are based on historical data from 1926–2024, inflation-adjusted. An 80/20 stock/bond allocation uses a 6.2% real mean with 14% standard deviation. A 60/40 allocation uses 5.3% real mean with 10.5% standard deviation. A 40/60 conservative allocation uses 4.3% real mean with 7% standard deviation. These are arithmetic means used to parameterize a log-normal distribution, which naturally produces the asymmetric return patterns observed in real markets.
- Is this financial advice?
- No. This calculator is an educational tool that runs projections based on historical data and the assumptions you enter. It does not account for taxes in detail, estate planning, healthcare cost shocks, or any number of individual circumstances that affect real retirement planning. The Monte Carlo simulation shows probability ranges, not guarantees. Consult a qualified financial advisor before making withdrawal rate decisions.
Disclaimer
This calculator is for educational and informational purposes only and does not constitute financial, tax, or investment advice. The projections are based on historical return distributions and the assumptions you enter — they are not predictions of future performance. Past performance does not guarantee future results. Monte Carlo simulations model probability ranges, not certainties. Individual circumstances including taxes, healthcare costs, market conditions, and personal spending patterns will significantly affect actual outcomes. Consult a qualified financial advisor, CPA, or tax attorney before making withdrawal rate or retirement planning decisions.
Go Deeper
A calculator is the start. The community is the edge.
FatFire members get peer-reviewed withdrawal strategies, coordinated tax optimization, vetted advisors who specialize in early retirement decumulation, and a community of people who've actually done this.