A thousand futures rather than one average one, so you can see the unlucky quarter as clearly as the lucky one and how long the pot holds in each.
$24,000/yr (4.8% rate)
Configure your retirement setup above and click Run Simulation.
Portfolio Lab includes guardrails spending strategies, 42 asset classes, 5 optimization methods, 23 years of backtesting, and 10,000-path simulations — all powered by J.P. Morgan data.
Try Portfolio Lab FreeThe tables below come from the same engine as the calculator above, with the same settings: 1,000 lognormal paths with fat-tail adjustment, seed 42, a $500,000 starting portfolio, annual rebalancing, a 0.5% management fee, and withdrawals that escalate with the simulated inflation path (centered on 2.5% a year). Enter matching inputs and the calculator reproduces every cell.
| 30-year survival | 3% | 3.5% | 4% | 4.5% | 5% |
|---|---|---|---|---|---|
| Conservative (30/60/10) | 99.1% | 95.0% | 77.9% | 55.0% | 30.8% |
| Balanced (60/30/10) | 96.7% | 89.2% | 77.7% | 63.8% | 49.6% |
| Aggressive (80/15/5) | 93.8% | 86.4% | 76.8% | 65.5% | 54.1% |
Withdrawal rates as monthly dollars on $500,000: 3% = $1,250, 3.5% = $1,458, 4% = $1,667, 4.5% = $1,875, 5% = $2,083.
At a 4% withdrawal rate the three mixes land within about a point of each other, near 78%. Allocation matters at the edges: at 3% a year the conservative mix survives most often (99.1%), while at 5% the aggressive mix does (54.1% against the conservative mix's 30.8%), because once withdrawals outrun bond yields only equity growth can keep pace.
| 4% rule survival | 20 yrs | 25 yrs | 30 yrs | 35 yrs | 40 yrs |
|---|---|---|---|---|---|
| Conservative (30/60/10) | 99.5% | 94.2% | 77.9% | 57.2% | 42.6% |
| Balanced (60/30/10) | 97.8% | 89.8% | 77.7% | 65.4% | 59.9% |
| Aggressive (80/15/5) | 95.1% | 87.0% | 76.8% | 66.6% | 63.2% |
Longer horizons separate the mixes the same way higher withdrawal rates do: past 30 years the equity-heavy allocations hold up better because they have more growth to outlast the extra years of withdrawals.
Survival means the portfolio never hits zero before the horizon ends; finishing with the starting balance intact is a stricter test. Figures computed August 2026 on the default assumptions with the calculator's stocks, bonds, and cash universe; they move when the assumptions do. Our updated Trinity Study analysis, which links withdrawals to simulated CPI rather than a fixed escalator, reports 79.7% for the same balanced mix.
Instead of assuming one fixed return every year, a Monte Carlo simulation generates thousands of possible market futures by drawing random returns from a statistical distribution, then measures how often your retirement plan survives across all of them. The output is a probability of success rather than a single yes/no answer, which reflects how uncertain markets actually are.
Yes. The simulator runs 1,000 paths entirely in your browser at no cost, with no signup required. A free Portfolio Lab account adds the full platform around it — the 42-asset optimizer, saved portfolios, and PDF reports — but the calculator itself is free to everyone.
It is only as good as its inputs. This calculator uses forward-looking return, volatility, and correlation assumptions averaged across 4 institutions rather than historical averages, and applies a Cornish-Fisher adjustment so the simulated returns have realistic fat tails instead of a pure normal distribution. No simulation predicts the future — treat the success probability as a stress test, not a guarantee.
This tool runs 1,000 paths, which is enough for the success probability to stabilize within about one percentage point. More paths sharpen the extreme percentiles slightly but rarely change the planning conclusion. What moves results far more is the quality of the return assumptions and whether fat tails are modeled.
Between 76.8% and 77.9% over 30 years, whether the mix is conservative, balanced, or aggressive — a $500,000 portfolio with the 4% rule's $1,667 a month escalating with simulated inflation (centered on 2.5% and correlated with returns), a 0.5% management fee, and J.P. Morgan 2026 assumptions. The original Trinity Study, tested on 1926-1995 US returns, put the 4% rule at 95% for a 50/50 portfolio; forward-looking assumptions are leaner, which is what pulls survival down.
This runs one plan on assumptions you type. The workstation runs your real holdings, with guardrails that cut spending when markets fall.
Open the workstation →