Monte Carlo retirement calculator
Run 1,000 possible market futures against your savings and spending to see how often the money lasts, how wide the range of outcomes is and how each withdrawal rate holds up.
Your retirement
Spending is what you need from the portfolio after Social Security and pensions, in today's dollars.
4.00% of the portfolio, rising with inflation
40% bonds
Standard deviation of yearly returns
Outcomes by year
Balances in today's dollars at the 10th, 50th and 90th percentiles, with the share of paths that ran out that year.
| Year | Poor | Median | Strong | Ran out |
|---|---|---|---|---|
| 1 | $871,000 | $992,221 | $1,119,872 | 0.0% |
| 2 | $802,856 | $981,803 | $1,174,814 | 0.0% |
| 3 | $741,497 | $972,325 | $1,228,587 | 0.0% |
| 4 | $699,475 | $954,678 | $1,235,244 | 0.0% |
| 5 | $665,489 | $958,012 | $1,297,028 | 0.0% |
| 6 | $632,451 | $945,617 | $1,328,870 | 0.0% |
| 7 | $597,248 | $925,337 | $1,343,714 | 0.0% |
| 8 | $561,542 | $920,021 | $1,393,280 | 0.0% |
| 9 | $535,902 | $906,805 | $1,398,645 | 0.0% |
| 10 | $507,866 | $910,709 | $1,424,287 | 0.0% |
| 11 | $470,006 | $891,323 | $1,441,067 | 0.0% |
| 12 | $433,797 | $869,222 | $1,499,980 | 0.0% |
| 13 | $397,582 | $866,257 | $1,540,587 | 0.0% |
| 14 | $354,194 | $858,551 | $1,583,541 | 0.1% |
| 15 | $326,244 | $833,885 | $1,602,646 | 0.1% |
| 16 | $291,717 | $817,295 | $1,664,763 | 0.1% |
| 17 | $254,874 | $814,157 | $1,703,441 | 0.5% |
| 18 | $229,356 | $795,059 | $1,712,433 | 0.5% |
| 19 | $188,572 | $763,435 | $1,714,154 | 1.2% |
| 20 | $144,316 | $756,370 | $1,778,359 | 1.0% |
| 21 | $108,943 | $730,591 | $1,776,607 | 1.4% |
| 22 | $73,525 | $689,544 | $1,855,490 | 1.3% |
| 23 | $35,037 | $672,567 | $1,854,639 | 2.1% |
| 24 | Depleted | $671,357 | $1,858,368 | 2.0% |
| 25 | Depleted | $653,308 | $1,868,249 | 2.6% |
| 26 | Depleted | $614,349 | $1,923,359 | 1.3% |
| 27 | Depleted | $586,188 | $1,952,967 | 2.0% |
| 28 | Depleted | $569,436 | $2,033,335 | 2.0% |
| 29 | Depleted | $555,756 | $2,023,024 | 2.4% |
| 30 | Depleted | $514,647 | $2,086,650 | 2.2% |
Success by withdrawal rate
The same market assumptions at seven starting rates. Each rate uses 600 paths.
| Rate | First year | Success |
|---|---|---|
| 3% | $30,000 | 94% |
| 3.5% | $35,000 | 88% |
| 4% | $40,000 | 78% |
| 4.5% | $45,000 | 64% |
| 5% | $50,000 | 51% |
| 5.5% | $55,000 | 36% |
| 6% | $60,000 | 24% |
Warren provides educational information, not individualized financial, tax or legal advice. Read our disclaimers.
Reading a simulation well
Look at the 10th percentile
The median shows the typical outcome, but you only get one retirement. The 10th percentile line tells you what a genuinely bad draw looks like and whether you could live with it.
Early failures matter most
A plan that fails in year 28 can be fixed with small spending cuts along the way. One that fails in year 12 cannot. The failure timing panel shows which kind you have.
Flexibility is worth a lot
Cutting spending by 10% after a down year raises success rates dramatically. Guardrail rules that raise spending in good times and trim it in bad ones let you start higher than a fixed 4%.
Test, do not optimise
Change one input at a time and watch the success rate. If a one-point drop in stock returns takes you from 90% to 60%, the plan is fragile regardless of the headline number.
Frequently asked questions
- What is a Monte Carlo retirement simulation?
- Instead of assuming the same return every year, it runs your retirement many times with returns drawn at random from a distribution with the average and volatility you expect. Each run is one possible future. The share of runs where the money never runs out is the probability of success. This tool runs 1,000 paths each time you change an input.
- What success rate should I aim for?
- Most planners look for 80% to 90%. A 100% result usually means you are spending less than you could, while below 75% leaves little room for a bad decade. Remember that a "failure" in the model is a plan that needed adjusting, not a catastrophe: real retirees cut spending, work a little or downsize when markets disappoint.
- What return and volatility assumptions are reasonable?
- US stocks have returned about 10% a year on average since 1928 with a standard deviation near 18%; many forecasters expect 7% to 9% from here. Intermediate bonds have returned about 4% to 5% with 6% to 8% volatility. The defaults here are deliberately a little conservative. Lower the stock return by a point or two to see how sensitive your plan is.
- Why do results differ from the retirement withdrawal calculator?
- That calculator uses a flat return every year, which hides the damage of bad early years. Monte Carlo shows the full range. If the median path here is similar to the flat projection but the 10th percentile runs out, your plan depends on luck in the first decade, which is exactly what the sequence-of-returns calculator explores with real history.
- What does this simulation leave out?
- Taxes, Social Security and pensions (subtract them from your spending need first), changing spending in retirement, correlation between stock and bond returns, and fat-tailed crashes bigger than a normal distribution predicts. Treat the success rate as a guide to how much margin you have, not a precise forecast.
Run the simulation on your real accounts
Warren AI uses your actual balances, Social Security estimate and spending from imported statements, then shows the odds and what would move them.