What Is a Safe Withdrawal Rate?
A safe withdrawal rate is the percentage of your retirement portfolio you could withdraw in the first year of retirement — then adjust that dollar amount for inflation every year after — with a reasonably high likelihood of not running out of money over your entire retirement. The most famous version of this idea is the "4% rule."
Where the 4% Rule Comes From
The 4% figure traces back to research by financial planner William Bengen in the mid-1990s, who tested historical U.S. market returns to find a withdrawal rate that would have survived even the worst historical stretches for a roughly 30-year retirement. Around the same time, a group of finance professors at Trinity University ran a broader version of this analysis — now widely known as the "Trinity Study" — testing various withdrawal rates and portfolio mixes of stocks and bonds against historical data. Both lines of research pointed to roughly 4% as a starting withdrawal rate that held up well historically for a 30-year retirement with a diversified stock-and-bond portfolio.
Why Sequence-of-Returns Risk Matters
This calculator assumes a constant, straight-line real return every single year — but real portfolios don't work that way. Two retirees can experience the exact same average annual return over 30 years and end up in very different places, depending on the order those returns arrive in. A retiree who experiences poor market returns in the first few years of retirement, while also withdrawing money, can permanently damage their portfolio's ability to recover — even if later years are strong. This is called sequence-of-returns risk, and it's the single biggest reason a simplified, average-return model like this one can be overly optimistic compared to what could actually happen.
Why Some People Use 3–3.5% Instead of 4%
The original 4% rule research was based on historical U.S. market data and a specific set of assumptions (portfolio mix, time horizon, fees). Because future returns, inflation, and the length of retirement are all uncertain — and some retirees plan for longer than 30 years, or want a larger margin of safety — many financial planners today recommend a more conservative starting rate, often in the 3% to 3.5% range, to reduce the risk of depleting a portfolio in a worse-than-historical scenario.
How to Use This Calculator
- Choose "Portfolio → Withdrawal" mode to see what a given portfolio can safely pay out, or "Spending → Portfolio" mode to see what portfolio size a target spending level would require.
- Enter your portfolio value (or desired annual spending).
- Set your withdrawal rate — 4% is the classic default, but you can test any rate from 2% to 8%.
- Enter your expected average annual real (inflation-adjusted) return during retirement, and your retirement length in years.
- Review the year-by-year projection table, and watch for the depletion warning if the portfolio is projected to run out.
Safe Withdrawal Rate Formulas
Worked Example
Year 1 withdrawal: $1,000,000 × 4% = $40,000.
Year 1 ending balance: $1,000,000 × 1.05 − $40,000 = $1,050,000 − $40,000 = $1,010,000. Because the 5% real return exceeds the 4% withdrawal rate, the portfolio actually keeps growing — by year 30 the projected balance is roughly $1.66 million in today's dollars, never dipping toward zero under this simplified model.
Reverse mode check: to support $40,000/year of spending at a 4% withdrawal rate, you'd need a portfolio of $40,000 ÷ 4% = $1,000,000 — matching the example above.
By contrast, a $1,000,000 portfolio withdrawing 6% ($60,000/year) against only a 4% real return is projected to be depleted around year 29 of a 30-year retirement — a clear illustration of why the gap between your withdrawal rate and your real return matters so much.
Understanding Your Results
The year-by-year table shows a straight-line projection: each year the portfolio grows by your assumed real return, then the flat annual withdrawal is subtracted. If the balance would hit zero, the calculator flags the year it happens. A portfolio that survives the full retirement length under these simplified assumptions isn't a guarantee it will in real life — it's a sanity check on whether your withdrawal rate is roughly in the right neighborhood given your return assumptions.
Important Considerations
- This is a simplified, deterministic model — it does not simulate market volatility, sequence-of-returns risk, or the chance of unusually bad early years, all of which can matter enormously in reality.
- It assumes a single constant real return every year, which never happens in real markets.
- It does not account for taxes, required minimum distributions, healthcare cost shocks, Social Security or pension income, or changes in spending needs over time.
- This tool is for educational purposes only and is not personalized financial advice — please consult a qualified financial advisor for your specific retirement plan.
Common Mistakes to Avoid
- Treating any fixed withdrawal rate as a guarantee rather than a starting point that should be revisited as markets and circumstances change.
- Ignoring sequence-of-returns risk — a few bad years early in retirement can matter more than the long-run average return.
- Using an overly optimistic expected real return, which makes a straight-line projection look far safer than reality is likely to be.
Frequently Asked Questions
It comes from historical research — most notably William Bengen's 1990s analysis and the later "Trinity Study" — that tested various withdrawal rates against actual historical U.S. market returns to find a rate that would have survived even the worst historical 30-year stretches with a diversified stock-and-bond portfolio.
It's debated. Many planners still view 4% as a reasonable starting point for a roughly 30-year retirement, but some now recommend 3% to 3.5% for extra safety margin, especially for longer retirements, lower expected future returns, or a lower tolerance for the risk of running out of money.
It's the risk that comes from the order in which investment returns occur, not just their long-run average. Withdrawing money during a market downturn early in retirement can permanently shrink a portfolio's ability to recover later — something a simple average-return projection like this one cannot capture.
No. It's a simplified, deterministic, straight-line projection using a single constant assumed return — not a Monte Carlo simulation or a forecast. It's meant as an educational starting point, not a guarantee, and shouldn't replace personalized advice from a financial advisor.
A nominal return is the raw, unadjusted market return. A real return subtracts out inflation, so it reflects growth in actual purchasing power. This calculator uses a real return and holds the annual withdrawal flat in real dollars, so the whole projection is expressed consistently in today's purchasing power, not future inflated dollars.