Safe Withdrawal Rate Calculator
Will your nest egg last? Stress-test your withdrawal rate with 1,000 simulations.
How This Calculator Works
Runs in your browser. No account. No saved financial data.
Formula
Each simulation starts with your portfolio, applies one random annual return, then subtracts that year's withdrawal.
Year 1 uses the withdrawal you entered. Later withdrawals inflate by your inflation setting.
Worked example
With $1,000,000, a $40,000 withdrawal, a deterministic 7% return, and 2.5% inflation, year 1 ends at $1,030,000. Year 2 withdraws $41,000 and ends at $1,061,100.
Assumptions
- Monte Carlo returns are drawn from a normal distribution using the selected stock/bond preset.
- A run succeeds if the portfolio remains above zero through the full horizon.
- Rate comparison reruns the model at 3%, 3.5%, 4%, 4.5%, and 5% starting withdrawal rates.
Limits
- Normal distributions can understate fat-tail market risk.
- Taxes, fees, cash buffers, Social Security, and spending guardrails are not included yet.
- Historical bootstrap mode would be a stronger future upgrade than pure random normal returns.
Withdrawal-rate sensitivity — terminal balance after 30 years
Deterministic projection of a $1,000,000 portfolio over 30 years, withdrawing at the listed starting rate (inflated 2.5% annually) and earning each allocation’s historical mean return. This is the no-volatility version of the Monte Carlo above — it shows where the math breaks even before sequence risk gets a vote.
| Allocation | Mean return | 3% SWR | 3.5% SWR | 4% SWR | 4.5% SWR | 5% SWR |
|---|---|---|---|---|---|---|
| Aggressive (90/10) | 10.2% | $12.1M | $11.0M | $9.9M | $8.9M | $7.8M |
| Growth (80/20) | 9.4% | $9.3M | $8.4M | $7.4M | $6.5M | $5.6M |
| Balanced (60/40) | 8.4% | $6.6M | $5.8M | $5.0M | $4.3M | $3.5M |
| Conservative (40/60) | 7.2% | $4.3M | $3.6M | $3.0M | $2.4M | $1.7M |
| Preservation (30/70) | 6.2% | $2.9M | $2.3M | $1.8M | $1.2M | $699k |
Mean returns flatter the picture — real markets sometimes deliver the same average through a much uglier sequence. Use the Monte Carlo above for sequence-of-returns risk and the failure-mode percentile.
What Is a Safe Withdrawal Rate?
A safe withdrawal rate is the starting percentage of a portfolio that a retiree withdraws in year one, usually with later withdrawals adjusted for inflation. A 4% withdrawal from a $1,000,000 portfolio starts at $40,000. If inflation is 3%, year two spending becomes $41,200. The question is not whether the first withdrawal works. The question is whether the portfolio can survive a long sequence of withdrawals, market returns, inflation, taxes, fees, and surprises.
The classic 4% rule is a useful benchmark, but it is not a universal answer. It was built around historical data, common U.S. stock/bond portfolios, and roughly thirty-year horizons. Early retirees often need longer horizons. A 50-year retirement gives bad markets more opportunities to show up and gives inflation more time to compound. That is why this calculator uses Monte Carlo simulation rather than a single fixed return. Instead of pretending every year earns the same return, it runs many possible return paths and reports success rates and percentile outcomes.
How to Read the Monte Carlo Results
Monte Carlo analysis is a stress-testing tool, not a forecast. Each run samples annual returns from the selected allocation's expected return and volatility profile. Some runs begin with good markets; some begin with losses. Some experience mediocre decades. The success rate is the share of runs that finish the full retirement horizon above zero. A 90% success rate means 10% of modeled paths failed under the assumptions, not that you have exactly a 10% real-world chance of failure.
The percentile balances show distribution, not certainty. A low 10th-percentile ending balance means the plan is sensitive to bad luck. A high median and low failure rate suggest more margin. If results are borderline, the usual levers are lowering spending, delaying retirement, adding part-time income, using a more flexible withdrawal rule, reducing fees, changing asset allocation, or choosing a lower initial withdrawal rate.
| Starting rate | Year-1 withdrawal from $1M | Typical use | Main caveat |
|---|---|---|---|
| 3.0% | $30,000 | Very long retirements or low flexibility | Requires a larger portfolio |
| 3.5% | $35,000 | Common conservative FIRE benchmark | Still depends on taxes and fees |
| 4.0% | $40,000 | Classic 30-year starting benchmark | May be aggressive for 50 years |
| 4.5% | $45,000 | Higher spending with flexibility or guardrails | More exposed to early losses |
30-Year vs 50-Year Retirement Horizons
Retirement length changes the interpretation of every result. A thirty-year horizon may fit someone retiring in their mid-sixties. A forty- or fifty-year horizon may fit a FIRE household leaving full-time work in their thirties or forties. Longer horizons do not only add more years of withdrawals; they add more chances for bad sequences, policy changes, healthcare shocks, and lifestyle drift. Read our 50-year safe withdrawal rate guide if your timeline is materially longer than a traditional retirement.
Also remember what the calculator does not model. Taxes can turn a gross withdrawal into a smaller after-tax budget. Investment fees reduce compounding. Social Security, pensions, annuities, and rental income can reduce portfolio withdrawals later. Flexible spending rules such as Guyton-Klinger guardrails may help a retiree adapt when markets are poor. For crash timing specifically, pair this page with the sequence of returns risk calculator.
Sources & References
The Monte Carlo defaults trace back to the Bengen and Trinity Study work, with Guyton-Klinger guardrails as a more flexible alternative. Return distributions are tuned against long-run S&P 500 (Shiller, FRED) and 10-year Treasury (FRED) data; inflation is grounded in BLS CPI.
- Determining Withdrawal Rates Using Historical Data — William P. Bengen, Journal of Financial Planning (1994)
Origin of the 4% rule. Tests fixed real-dollar withdrawals against U.S. equity and bond returns from 1926.
- Retirement Savings: Choosing a Withdrawal Rate That Is Sustainable — Cooley, Hubbard, Walz — Trinity University (1998, AAII Journal)
Trinity Study. Reports portfolio success rates for 15–30 year retirements at withdrawal rates from 3% to 12%.
- Decision Rules and Maximum Initial Withdrawal Rates — Jonathan Guyton & William Klinger, Journal of Financial Planning (2006)
Source for the Guyton-Klinger flexible-withdrawal guardrails referenced throughout the SWR guides.
- Historical U.S. Stock Market Data — Robert J. Shiller, Yale University
Long-horizon S&P composite price, earnings, and dividend data, the standard academic dataset for historical SWR analysis.
- S&P 500 Index — FRED — Federal Reserve Bank of St. Louis
Public S&P 500 series. Used when articles report long-run U.S. equity return averages.
- 10-Year Treasury Constant Maturity Rate (DGS10) — Federal Reserve Bank of St. Louis
Benchmark long-term Treasury yield used for bond-return assumptions in SWR and sequence-risk models.
- Consumer Price Index (CPI-U) — U.S. Bureau of Labor Statistics
Headline CPI series. Default inflation assumptions in calculators are calibrated against long-run CPI averages.
Frequently Asked Questions
What is Monte Carlo simulation?
Monte Carlo simulation runs thousands of possible market scenarios using historical return distributions. Instead of assuming a fixed return, each simulation applies random yearly returns drawn from a normal distribution matching your asset allocation's historical characteristics.
What is a safe withdrawal rate?
The safe withdrawal rate (SWR) is the percentage of your portfolio you can withdraw annually without running out of money. The '4% rule' from the Trinity Study found that 4% survived most 30-year periods historically.
What is sequence of returns risk?
Sequence risk means poor market returns in early retirement years can deplete your portfolio even if average returns are normal. Monte Carlo simulation captures this risk because each simulation has a different sequence of returns.
How many simulations are run?
We run 1,000 simulations per analysis. Each simulation generates random annual returns based on the historical mean and standard deviation for your selected asset allocation (e.g., 60/40 stocks/bonds).
What do the allocation presets mean?
Each preset represents a stock/bond split with historically calibrated return distributions. Aggressive (90/10) has higher expected returns but more volatility. Conservative (40/60) has lower returns but smoother outcomes.