Retirement Success Probability Calculator
Probability your plan survives, from expected real return and volatility — the lognormal approximation to a Monte Carlo.
Formula
Volatility, not just average return, decides survival — the same 4.5% real return at 18% vol fails far more often than at 10%. Real plans add the flexibility this math can't see: cutting withdrawals 10% in drawdown years lifts success rates dramatically.
Not financial advice — for informational and analytical use only. Verify all figures with a qualified professional before acting on them.
Disclaimer: This tool is for general informational and estimation purposes only and is not professional financial, tax, accounting or legal advice. All figures are estimates — verify with a qualified professional before making decisions. Read the full disclaimer.
Need retirement success probability calculator results fast? Analysts, founders, traders and finance professionals use the Retirement Success Probability Calculator to skip the spreadsheet and get a defensible answer in one step — free, private and instant.
About Retirement Success Probability Calculator
Probability your plan survives, from expected real return and volatility — the lognormal approximation to a Monte Carlo. Volatility, not just average return, decides survival — the same 4.5% real return at 18% vol fails far more often than at 10%. Real plans add the flexibility this math can't see: cutting withdrawals 10% in drawdown years lifts success rates dramatically. The governing relationship is P ≈ N[ (μ−w−σ²/2)·T / σ√T ] — geometric survival approximation. The Retirement Success Probability Calculator computes entirely in your browser — free, private (your figures never leave your device) and instant, recalculating live as you change any input.
How to use Retirement Success Probability Calculator
- 1Enter Corpus (currency), Annual withdrawal (real) (currency), Expected real return (%), Portfolio volatility (%), Plan length into the Retirement Success Probability Calculator.
- 2The result is computed automatically using P ≈ N[ (μ−w−σ²/2)·T / σ√T ] — geometric survival approximation — there is no button to press.
- 3Change any input to model a different scenario, then copy or share the result.
Why use Retirement Success Probability Calculator?
- ✓Computes retirement success probability calculator instantly with the correct formula — no spreadsheet needed
- ✓100% free and unlimited, with no sign-up, login or paywall
- ✓Runs entirely in your browser, so the figures you enter stay private
- ✓Shows the formula, a live worked example and references so you can defend the number
Frequently asked questions
What is the formula behind the Retirement Success Probability Calculator?+
Retirement Success Probability Calculator uses P ≈ N[ (μ−w−σ²/2)·T / σ√T ] — geometric survival approximation. Volatility, not just average return, decides survival — the same 4. The tool substitutes your actual inputs into this relationship and shows the worked example step by step.
What inputs does the Retirement Success Probability Calculator need?+
Enter Corpus (currency), Annual withdrawal (real) (currency), Expected real return (%), Portfolio volatility (%), Plan length and the result updates immediately — there is no button to press. Change any value to model a different scenario in real time.
Is the Retirement Success Probability Calculator free, and is my data private?+
Yes — it is completely free with no sign-up or usage limit, and it runs entirely in your browser, so the numbers you enter are never uploaded or stored on any server. It is for informational and analytical use, not financial advice.
What should I watch out for when using the Retirement Success Probability Calculator?+
5% real return at 18% vol fails far more often than at 10%. Real plans add the flexibility this math can't see: cutting withdrawals 10% in drawdown years lifts success rates dramatically.
What is the Retirement Success Probability Calculator based on?+
The method follows authoritative sources: Milevsky — sustainable spending under uncertainty. The formula and references are shown on the page so you can verify and cite the result.
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