The 4% Rule Explained: How Much You Really Need to Retire

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Multiply your portfolio by 4%. That number is what most retirees can safely spend each year for 30 years without running out of money. A $1 million portfolio supports $40,000 per year. A retiree who needs $50,000 per year of portfolio income needs $1.25 million. The math is simple, the assumptions are not, and the rule has been revised more than once since it was first published.

Key takeaways

• The 4% rule comes from the 1998 Trinity Study and assumes a 50/50 stock and bond portfolio over a 30-year retirement.
• Bill Bengen, who first published the original 4% number in 1994, has since revised his guidance upward to 4.7% when global diversification is included.
• Morningstar's 2024 research suggests a 3.7% starting withdrawal is more realistic given today's bond yields and equity valuations.
• Sequence-of-returns risk in the first ten years matters more than the average return over 30 years.
• The bucket strategy is a practical alternative that keeps two to three years of expenses in cash to ride out market drawdowns.

Where the 4% rule actually came from

The number traces to two papers. Bill Bengen, a financial advisor, ran a 1994 study using historical US market data going back to 1926. He found that a retiree drawing 4% of a starting portfolio, then adjusting that dollar amount for inflation each year, would have survived every 30-year window in history. Four years later, three professors at Trinity University in San Antonio reran the analysis with different asset mixes and confirmed the result. Their paper, now called the Trinity Study, is the source of the 95% historical success rate that gets quoted everywhere.

The exact assumptions

• Portfolio: 50% S&P 500, 50% intermediate-term government bonds.
• Horizon: 30 years.
• Withdrawal: 4% of the starting balance in year one, then that dollar amount adjusted for CPI each year after.
• Success: any ending balance above zero, even one dollar.

The math: how to turn the rule into a number

Two formulas. Use whichever you have.

Forward: portfolio to income

Portfolio × 0.04 = annual withdrawal

A $750,000 portfolio supports $30,000 per year. A $2 million portfolio supports $80,000 per year.

Reverse: income to portfolio

Annual expenses ÷ 0.04 = portfolio needed

Or, more usefully, multiply expenses by 25.

The spread is wide. A retiree needing $80,000 a year sees a target between $1.7 million and $2.16 million depending on which rate they trust. The honest answer is that the right number sits somewhere in that range.

The 2026 picture: what changed since 1998

Two things moved the goalposts after the original Trinity work.

Bond yields collapsed, then partially recovered

The original 4% number was tested through decades when intermediate Treasuries paid 5% to 7% in real terms. From 2010 to 2022, real bond yields were near zero. That alone broke the math. Yields have since climbed back, with 10-year Treasury Inflation-Protected Securities around 2% real in 2026, which restores some of the original cushion but not all of it.

Bengen revised his own rule upward

In his 2023 book and a series of follow-up interviews, Bill Bengen raised his recommendation to 4.7%. The reason is global diversification. The original study used only US large-cap stocks. Adding small caps, international equities, and real assets reduced volatility enough to support a higher safe rate. This is the most aggressive mainstream number on the table.

Morningstar runs the other direction

Morningstar's annual State of Retirement Income report uses forward-looking returns rather than historical ones. Their 2024 number is 3.7% for a 30-year horizon and a balanced portfolio. The logic: starting valuations matter. When stocks are expensive and bond yields are mediocre, future returns tend to disappoint.

The 4% number was never a promise. It was the worst-case historical result. Whether 3.7% or 4.7% is closer to today's worst case depends entirely on what happens in the first decade of your retirement.

Sequence-of-returns risk: why the first ten years matter most

Two retirees can have the same 30-year average return and end up in completely different places. The retiree who hits a bear market in year two is in real trouble. The retiree who gets a bull market first and the bear at year 25 finishes rich. This is sequence risk, and it is the single largest threat the 4% rule has to absorb.

A worked example

Two retirees, both starting with $1 million, both withdrawing $40,000 per year, both earning an average 7% return over 30 years. Retiree A gets minus 20% in year one, minus 10% in year two, then good returns. Retiree B gets the same returns in reverse order. Retiree A runs out of money at year 23. Retiree B finishes with over $2 million. Same average, opposite outcome.

Practical defenses against sequence risk

• Hold two to three years of expenses in cash or short Treasuries to avoid selling stocks in a drawdown.
• Use a flexible withdrawal rule like Guyton-Klinger guardrails: cut spending 10% if the portfolio drops below a threshold, raise it 10% if it grows past another.
• Delay Social Security to 70, which adds roughly 8% per year of guaranteed inflation-linked income on top of the portfolio.
• Consider a single-premium immediate annuity for a base layer of fixed income, reducing the portfolio share that needs to be withdrawn.

The bucket strategy alternative

The bucket approach abandons the single-pool 4% framing in favor of three time-segmented accounts.

When stocks fall, the retiree spends from buckets 1 and 2 and lets bucket 3 recover. When stocks rise, they sell equities to refill buckets 1 and 2. The psychological benefit is real: no one is forced to sell stocks at the bottom.

Editor's pick: where to actually hold the buckets

A single brokerage account is enough to hold all three buckets. Fidelity, Vanguard, and Schwab all support fractional shares, automatic rebalancing, and zero-commission ETF trading. Opening a brokerage with a Cash Management feature at Fidelity gives a checking-like sweep for bucket 1 alongside the investment buckets. For ultra-safe bucket 1 holdings, buying 4-week and 8-week T-bills through TreasuryDirect avoids any brokerage middleman.

What the 4% rule does not cover

• Taxes. The 4% withdrawal is gross. In a taxable account, federal and state tax reduce the spendable number by 10% to 25%.
• Healthcare. Pre-65 retirees buying ACA coverage may spend $15,000 to $25,000 per year on premiums alone.
• Long-term care. The median nursing home cost in 2026 exceeds $110,000 per year. The 4% rule does not finance this.
• Lumpy spending. A new roof, a car replacement, a wedding gift to a child — these break the smooth inflation-adjusted withdrawal pattern.

How much you really need: three honest scenarios

The lean retiree

Paid-off house, modest spending of $40,000 per year, full Social Security at 67 of $30,000. The portfolio only needs to cover $10,000 per year. At 4%, that is $250,000.

The middle-class retiree

$70,000 per year of spending, Social Security of $36,000, gap of $34,000. At 4%, the portfolio target is $850,000. At Morningstar's 3.7%, it is $920,000.

The high earner

$140,000 per year, Social Security of $45,000, gap of $95,000. At 4%, the portfolio target is $2.375 million. This is the group for whom the 3.7% versus 4.7% debate matters most: the difference is $470,000 of additional savings.

How to use the rule today

1. Estimate annual spending in retirement dollars, including healthcare.
2. Subtract guaranteed income (Social Security, pension, annuity).
3. Multiply the gap by 25 for the 4% baseline, or by 27 for a more conservative 3.7% baseline.
4. Add a healthcare reserve if retiring before 65.
5. Add 1 to 2 years of cash for sequence-risk defense.

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FAQ

Is the 4% rule still valid in 2026?

Yes, with adjustments. The original 4% number remains a reasonable starting point for a 30-year retirement and a balanced portfolio. Most current research places the safe withdrawal range between 3.7% and 4.7% depending on the assumptions used. The rule has survived rising interest rates, falling interest rates, and two market crashes since it was published.

What is the difference between the 4% rule and the 25x rule?

They are the same math. The 4% rule says withdraw 4% of the portfolio. The 25x rule says save 25 times annual expenses. One divided by 0.04 equals 25, so they describe the identical target from opposite directions.

Does the 4% rule include Social Security?

No. The 4% rule only applies to portfolio withdrawals. Social Security and any pension income are separate guaranteed streams that reduce the dollar amount the portfolio needs to cover.

What portfolio does the 4% rule assume?

A 50% stock, 50% bond mix. Bengen's original work tested 50/50 and 75/25 stock/bond splits and found both worked. Going below 40% in stocks reduced the safe withdrawal rate because long-term growth fell off too quickly.

What happens after 30 years?

The Trinity Study only ran 30-year windows, so the rule says nothing about year 31. Retirees expecting to live past 95 should either lower the starting withdrawal to roughly 3.5% or plan to revisit the math at age 80.

Should I adjust withdrawals during bear markets?

Yes, if possible. The pure 4% rule is rigid: same inflation-adjusted dollar amount every year. Flexible rules like Guyton-Klinger guardrails reduce spending 10% in bad years and add 10% in good years, which historically supports a higher starting rate, closer to 5%.

Is the 4% rule too conservative?

For most US retirees historically, yes. The 4% rule was the worst case, not the average. In most 30-year periods, retirees who followed it ended with more money than they started with. The conservatism is the point. It is a floor, not a forecast.

What is sequence-of-returns risk?

The risk that poor market returns in the early years of retirement permanently shrink the portfolio, even if the long-term average is fine. Two retirees with the same 30-year average return can have wildly different outcomes depending on the order of those returns.

How does the 4% rule treat inflation?

Withdrawals start at 4% of the initial portfolio and then rise with CPI each year. A retiree starting with $40,000 of withdrawals would take roughly $41,200 the next year if inflation was 3%, regardless of portfolio performance.

What if I retire early at 50 or 55?

Lower the starting rate. A 40-year retirement supports closer to 3.3% to 3.5% safely. The FIRE movement often uses 3.5% to 3.75% for this reason.

Bottom line

The 4% rule is the cleanest piece of retirement math ever produced, and it remains the right starting point in 2026. Take expected annual spending, subtract guaranteed income, multiply the gap by 25, and the answer is close enough to act on. Then build in the defenses the rule does not provide: cash for sequence risk, a healthcare reserve if retiring early, and a willingness to flex spending in bad market years. The number is not the plan. The number is the entry point to the plan.