Monte Carlo Retirement Calculator
Enter a starting balance, what you add each year until retirement, and what you plan to withdraw each year after. This runs 2,000 simulated paths, each with its own sequence of annual returns drawn from a lognormal distribution with the mean and standard deviation you set, and reports how many paths never ran out of money, with the spread of balances along the way. Free, no signup.
What this assumes
One return per year, independent of every other year, drawn from a lognormal distribution. No fees, no taxes, no Social Security or other income. Inflation is constant at the rate you enter, and the withdrawal you type is in today’s dollars, so it is already larger by the time retirement starts and keeps growing every year. Contributions land at the end of each accumulation year; withdrawals come out at the start of each retirement year. A balance that reaches zero stays at zero. The paths are seeded, so the same inputs always print the same numbers. Illustrative only, not a forecast, not advice.
Your plan
The return distribution
2,000 paths over 45 years
Success rate
83.1%
1,662 of 2,000 paths never reached zero. Among the 338 that did, the median ran out in year 37, 22 years into retirement.
Median balance at retirement
$2,052,628
After 15 years of returns and contributions. Half the paths finished above this, half below.
First-year withdrawal
$80,752
Today's withdrawal after 15 years of inflation. It reaches $143,403 in the last year.
Where the balance lands
Each row is a rank across the 2,000 paths, in nominal dollars. The 10th percentile is the balance that nine paths in ten finished above; the 90th is the one that only one in ten exceeded. A zero at the end means that rank of path ran out of money.
| Rank | At retirement (year 15) | At the end (year 45) |
|---|---|---|
| 10th percentile | $1,233,456 | $0 |
| 25th percentile | $1,563,346 | $1,553,359 |
| Median | $2,052,628 | $7,252,053 |
| 75th percentile | $2,720,445 | $17,230,951 |
| 90th percentile | $3,517,653 | $30,529,677 |
The band, every 5 years
Year-end balances at the 10th, 50th and 90th percentile, plus the retirement boundary and the final year. The band widens over time because each year’s return compounds on the last.
| Year | Phase | 10th | Median | 90th |
|---|---|---|---|---|
| 0 | Today | $500,000 | $500,000 | $500,000 |
| 5 | Saving | $622,727 | $845,231 | $1,150,335 |
| 10 | Saving | $870,249 | $1,345,262 | $2,063,550 |
| 15 | Saving | $1,233,456 | $2,052,628 | $3,517,653 |
| 20 | Retired | $1,119,685 | $2,459,569 | $4,973,876 |
| 25 | Retired | $952,916 | $2,970,232 | $7,134,540 |
| 30 | Retired | $711,753 | $3,661,601 | $10,303,924 |
| 35 | Retired | $271,915 | $4,450,039 | $14,518,418 |
| 40 | Retired | $0 | $5,637,759 | $21,150,102 |
| 45 | Retired | $0 | $7,252,053 | $30,529,677 |
The part a simulation cannot do
This page draws returns for a single balance. It does not know what that balance is made of, how concentrated it is, or what its own volatility has been. Helm reads the holdings in the accounts you connect, read-only, and shows the exposure across all of them: what each position is, what share of the whole it carries, and what moved it. It cannot see accounts you have not connected.
See your own bookHow the paths are built
Every path starts from the same balance. For each year, the simulation draws one return from a lognormal distribution set so that the simple annual return has the arithmetic mean and standard deviation entered above, and each draw is independent of every other year and every other path. During accumulation the balance earns that return and then the contribution is added. During retirement the inflated withdrawal comes out first and what is left earns the return. A balance that reaches zero stays at zero and the path is counted as a failure. The random draws come from a seeded generator, so the same inputs always print the same numbers, and changing the number of paths changes the sample rather than the method.
Nothing else is in the model. There are no fees, no taxes, no Social Security, no pension, no change in the withdrawal when the balance is high or low, and no relationship between one year’s return and the next.
What the defaults are
The default return of 8.41 percent and volatility of 12.94 percent are the average annual NAV total return since inception (May 15, 2000) and the three-year standard deviation printed on the iShares Core S&P 500 ETF product page, read September 16, 2026. They describe one fund’s past. The three-year standard deviation in particular covers a calm stretch, and a longer history of the same index runs higher, which is one reason the field is editable. The default inflation rate of 2 percent is the Federal Reserve’s stated longer-run objective, not a measurement of any year.
Frequently asked questions
What is a Monte Carlo retirement calculator?
A calculator that, instead of assuming one fixed return every year, draws a different random return for each year of each simulated path and runs the plan many times. This one runs 2,000 paths by default, each with its own sequence of annual returns drawn from a lognormal distribution with the mean and standard deviation entered on the page. The output is the spread of outcomes across those paths, not a single projection.
What does the success rate mean?
The share of simulated paths whose balance never reached zero before the last year of retirement. A success rate of 83 percent means 83 out of every 100 paths, under the stated return distribution and withdrawal schedule, stayed above zero the whole way. It is a property of the simulation and its assumptions, not the probability of any real outcome.
Why does the success rate fall when volatility rises but the expected return stays the same?
Because withdrawals make the order of returns matter. A bad year early in retirement removes money that would have compounded through every later year, and a fixed withdrawal takes a larger slice of a smaller balance. Higher volatility puts more paths through that sequence, so more of them run out, even though the average return across all the paths is unchanged.
Where do the default return and volatility come from?
From the product page of the iShares Core S&P 500 ETF, IVV: an average annual NAV total return of 8.41 percent since the fund's inception in May 2000, and a three-year standard deviation of 12.94 percent. The return is a 26-year average of one index fund and the standard deviation covers only the last three years, so both fields can be changed. The default inflation rate of 2 percent is the Federal Reserve's stated longer-run objective.
Why is the withdrawal entered in today's dollars?
Because a withdrawal that stays fixed in nominal dollars buys less every year. The page takes the amount you type, inflates it at the entered rate for every year until retirement, and then keeps inflating it through retirement, so the first-year withdrawal it shows is already larger than the number you entered and the last-year withdrawal is larger still. The balances it reports are nominal, in the dollars of each future year.
Related reading
Illustrative only, not a forecast, not advice. The figures are random draws from a distribution you chose, applied to the numbers you typed. The pages linked above win if they differ from anything on this page.