Safe Withdrawal Rate Backtester
How often your withdrawal rate would have survived US market history
Safe Withdrawal Rate Backtester
Historical success rate estimate
0%
of rolling US historical periods that didn't run out of money
On $1,000,000 portfolio
0
first year's withdrawal
The 4% rule was never a guarantee
The original Trinity-study research found roughly a 95% historical success rate for a 4% withdrawal rate over 30 years at a 50-75% equity allocation — a strong track record, not a certainty, and based entirely on the specific historical US market periods that happened to occur.
Longer horizons need lower rates
A 30-year retirement and a 50-year retirement (common for FIRE retirees in their 30s-40s) have very different failure dynamics — the same 4% that looks safe over 30 years shows meaningfully more historical failures stretched over 45-50 years.
Equity allocation matters more than people expect
Very low equity allocations (heavy bonds/cash) historically fail MORE often at a given withdrawal rate than a balanced 50-75% equity mix, because they can't outpace inflation and sequence-of-returns drag over multi-decade retirements — "safer-feeling" isn't always safer.
Success-rate estimates are a simplified approximation built from published historical safe-withdrawal-rate research (Bengen, the Trinity study, and subsequent updates) using their published rolling-period success rates as reference points and interpolating between them — this is NOT a live Monte Carlo simulation or a real historical backtest of your specific inputs. Past US market history, however favorable, is not a guarantee of future returns; sequences of returns, inflation, and fees can all differ going forward. Use this as a directional estimate, not a precise probability, and consider consulting a fee-only financial planner for an actual retirement income plan. Not financial advice.
Frequently asked questions
How much do I actually need to retire comfortably?
It depends on your expected retirement expenses, Social Security benefit, and life expectancy -- there's no single universal number, though rules of thumb like "25x annual expenses" are a common starting point. This calculator lets you build a more specific estimate from your own numbers.Read more: Social Security Estimator: Why Claiming Age Changes Everything
What's the difference between a 401(k) and an IRA?
A 401(k) is employer-sponsored, often with an employer match, and has a higher annual contribution limit. An IRA is opened independently at a brokerage, with a lower contribution limit but typically far more investment choice. Many people contribute to both -- a 401(k) up to the employer match, then an IRA.Read more: Roth vs Traditional Calculator: Pay Tax Now or Pay Tax Later?
When should I claim Social Security -- 62, 67, or 70?
Claiming at 62 gives a permanently reduced benefit; waiting until your full retirement age (typically 66-67) gives the full benefit; waiting until 70 gives the maximum benefit, growing roughly 8% per year you delay past full retirement age. The right age depends on your health, other income, and whether you need the money sooner.Read more: Retirement Number Calculator: How Much Is Actually Enough?
How does inflation affect my retirement savings?
Inflation erodes purchasing power both before and during retirement, so a nominal dollar figure that looks sufficient today can fall short decades from now. This calculator shows results in both nominal and inflation-adjusted terms so you're not planning around a number that quietly loses value.Read more: Social Security Estimator: Why Claiming Age Changes Everything
Estimates only, not financial advice. See our Disclaimer.