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RetireCast

Answer three questions and see what your retirement could look like.

How much have you saved so far? All accounts combined — 401k, IRA, brokerage, savings

How much will you save each year? Your total annual contributions across all accounts

How many years until you retire? E.g. if you're 35 and want to retire at 65, enter 30

Your retirement outlook in a typical market

Tough Years

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1-in-10 chance of this or less

Most Likely

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Median outcome

Great Years

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1-in-10 chance of this or more

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Estimated monthly income (most likely scenario)

Based on 4% withdrawal rule · today's dollars

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Your range of possible futures

10,000 simulated paths · shaded band shows where most outcomes land

⚠ For educational purposes only. Not financial advice. Numbers assume a typical stock market average (~5.8% annual return). Actual results depend on many factors not modeled here — inflation, taxes, fees, and life events.

Want to see different market scenarios, stress test a crash, or model a glide path?

RetireCast

Monte Carlo Retirement Forecast

$7,500/yr · Monte Carlo 10,000 paths · 2026–2050 · Starting $8,492.71

$8,492.71

Starting Balance

2026 Post-Tax Limits (IRS) Roth IRA $7,500 (under 50) Roth IRA 50+ $8,600 Roth 401(k) $24,500 Roth IRA + 401(k) $32,000 Numbers not adjusted for tax · Verify at IRS.gov

⚠ Tax disclaimer: Projections do not account for taxes on withdrawals from 401(k) or other tax-deferred accounts. Traditional 401(k) and IRA withdrawals are taxed as ordinary income in retirement. Roth accounts grow and withdraw tax-free. Actual after-tax retirement income will differ — consult a tax advisor for your specific situation.

⚠ Disclaimer: For educational and entertainment purposes only. Not financial advice. Not affiliated with Vanguard, Fidelity, BlackRock, or any financial institution. Past market performance does not guarantee future results. Consult a licensed financial advisor before making investment decisions.

▶ ▶ View Modeling Assumptions

Simulation Framework
• 10,000 Monte Carlo paths · Annual contributions added at end of period · HIST/HIST-R use block bootstrap (size 4)

Return Modeling
• BEAR/BASE/BULL/OPT: normally distributed returns (μ, σ) · HIST: block bootstrap S&P 500 1928–2025 · HIST-R: block bootstrap 2000–2025

Glide Path
• σ tapers linearly from start to end σ · μ optionally tapers to bond-like drift

Limitations
• No taxes, fees, or withdrawal rules modeled · Assumes constant contributions · Probabilistic estimates only

Portfolio & Timeline

Starting Balance Your total current portfolio value

Start Year First year of simulation

End Year Target retirement year

Annual Contributions by Account

Roth IRA 2026 max: $7,500 (under 50) · $8,600 (50+)

401(k) / Roth 401(k) 2026 max: $24,500 employee · Pre or post-tax

Taxable Brokerage No limit · Capital gains tax applies on withdrawal

Other (HSA, 403b, etc.) Any additional tax-advantaged contributions

Total Annual Contribution $7,500

⚠ Tax note: 401(k) projections show pre-tax growth. Withdrawals will be taxed as ordinary income. Roth accounts grow and withdraw tax-free. Taxable brokerage subject to capital gains.

Inflation & Withdrawal

Annual Inflation Rate Default 2.9% — Fed long-run target ~2.0–3.0%

Safe Withdrawal Rate Classic "4% rule" — annual withdrawal as % of portfolio

Numbers stay in your browser — nothing is saved or sent anywhere.

Projected Outcomes by End Year

Mean

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Median

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10th %ile

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25th %ile

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75th %ile

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90th %ile

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Inflation-Adjusted (Real) Values · Today's Dollars

Real Median

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Real 10th %ile

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Real 25th %ile

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Real 75th %ile

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Real 90th %ile

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Inflation Factor

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Annual Withdrawal Capacity

Based on 4.0% safe withdrawal rate

Nominal & inflation-adjusted (today's $)

Median Nominal

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per year

Median Real

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per year · today's $

10th %ile Real

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per year · today's $

90th %ile Real

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per year · today's $

Monthly Real

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per month · today's $

ℹ The 4% rule (Bengen 1994) suggests withdrawing 4% of your portfolio in year 1, then adjusting for inflation each year — historically lasting 30+ years.

Probability of Reaching Target by End Year

Simulation Fan Chart

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⟳ Glide Path Active — Volatility Tapering

—σ tapering →—

🐻 Late Bear Stress Test

Forces the final N years of every path to a fixed crash return. Tests sequence-of-returns risk.

Bear Years at End3 years

Forced Annual Return−30%

📉 Glide Path Mode

Tapers volatility σ linearly from full-equity levels toward bond-like levels near retirement.

Glide Path Disabled

End-Year Outcome Distribution

Histogram of ending portfolio values

Scenario Comparison

Median end-year value — all forecasts side by side

US Stock Market Annual Returns

S&P 500 historical performance — context for scenario assumptions

Simulation Summary

Your current inputs

Starting balance$8,492.71

Annual contribution$7,500.00

Weekly equivalent~$144.23/wk

Time horizon25 years (2026–2050)

Total contributions$187,500

Forecast Source	Horizon	US Equity μ
Vanguard VCMM	5–10 yr	4.0%–5.0%
Fidelity CMA	20 yr	5.8% nominal
BlackRock	10 yr	~5.2%
Vanguard 30yr	30 yr	4.4%–6.4%
Historical avg	Long-run	~8.0%