Penny Runs the Numbers

Early Retirement Monte Carlo Calculator: Can You Retire at 35?

Real US returns since 1928, after inflation. Move the sliders.
Portfolio at retirement
Spending per year
Stocks / bonds
S&P 500 / 10-year Treasuries, rebalanced yearly
Money must last
Never ran out
Left at the end
Spend for 90% success

Portfolio in today's dollars

Median run Middle 50% Middle 80% Unluckiest 10%

Retiring at 35 with $1.9 million and spending $25,000 a year (1.32%), 9,957 of 10,000 simulated retirements never run out of money over 60 years (80% stocks, 20% bonds, real US returns 1928–2025). At the 4% rule ($76,000 a year) only 77.8% last to age 95. The highest spending with at least 90% success is $56,000 a year.

How the simulation works

The calculator uses every calendar year from 1928 to 2025: the S&P 500 total return, the 10-year US Treasury total return and that year's inflation. It draws those years at random, with replacement, to build 10,000 possible 60-year futures. Stock, bond and inflation numbers always come from the same historical year, so a bad year for stocks keeps its matching bond and inflation figures.

Each year you take your spending out first, then the rest earns that year's return after inflation. Spending stays fixed in today's dollars. A retirement counts as a success if the money never runs out before the end of the horizon. The random draws use a fixed seed, so everyone sees the same 10,000 futures.

Why the 4% rule is too high for a 60-year retirement

The 4% rule comes from studies of 30-year retirements. Retiring at 35 means the money has to last about twice as long, and a longer run gives a bad stretch of markets more time to drain the pot. With $1.9 million, 80% stocks and 60 years, spending $40,000 a year still succeeds 97.2% of the time, $56,000 succeeds 90.6% of the time and $76,000 (4%) only 77.8%.

Over 30 years the same $76,000 succeeds 89.5% of the time in this simulation, so the horizon matters as much as the rate.

Are bonds safer for early retirees?

Not over 60 years. From 1928 to 2025, 10-year Treasuries beat inflation by only about 1.5% a year, against about 6.8% for stocks. Spending 4% from an all-bond portfolio succeeds in just 5.5% of the simulated retirements, while 50% stocks reaches 67.8% and 80% stocks 77.8%.

At low spending the mix matters less: at $25,000 a year, all bonds still succeeds 95.2% of the time and 80% stocks 99.6%.

Questions

Can you retire at 35 with $1.9 million?

In this simulation, yes if spending is modest. At $25,000 a year (1.32% of the portfolio), 99.6% of 10,000 simulated 60-year retirements never run out of money. At $76,000 a year (the 4% rule) the success rate drops to 77.8%.

What is a safe withdrawal rate for early retirement?

With 80% stocks and a 60-year horizon, the highest spending with at least 90% success is $56,000 a year on $1.9 million, about 2.9% of the starting portfolio. For 95% success it is $46,000 a year. Move the sliders to test your own portfolio and time frame.

Where do the returns come from?

Annual S&P 500 and 10-year Treasury total returns for 1928–2025 from Aswath Damodaran's historical returns data (NYU Stern), adjusted for inflation with the December-to-December change in the CPI-U from the U.S. Bureau of Labor Statistics.

What does this calculator leave out?

Taxes, fund fees, Social Security, pensions and side income. Spending never adjusts to markets. Years are drawn independently, so long runs of good or bad years can be shorter or longer than in real history. It is a model of the past, not a forecast.

Sources and assumptions

Last updated 2026-11-11.