The 4% rule explained — is it still valid in 2026?

The 4% rule says you can withdraw 4% of your retirement portfolio annually, adjusted for inflation each year, and your money will last 30 years. It's the most cited benchmark in retirement planning — and it's currently being revised. Morningstar's 2026 research suggests 3.9% as the conservative baseline. Bill Bengen, who created the rule, now puts it at 4.7%. Here's what the rule actually means, what changed, and how to use it correctly.

What the 4% rule actually is

The 4% rule is a retirement withdrawal guideline: in your first year of retirement, withdraw 4% of your total portfolio. In each subsequent year, adjust that dollar amount for inflation — regardless of what the market did. If you do this, historical data suggests your portfolio has survived every 30-year period in U.S. market data under the original study assumptions.

The rule has two practical implications that most people know:

Note: Most withdrawal rate research assumes low investment fees and pre-tax returns. Higher investment costs or taxes on withdrawals can meaningfully reduce sustainable withdrawal rates in practice.

• The 25x rule (accumulation side): To retire safely, you need to save 25 times your annual expenses. This is simply the inverse of 4% — if you withdraw 4%, you need 25x to make it work. $50,000/year in expenses = $1.25M needed. $80,000/year = $2M needed.
• The withdrawal rate (decumulation side): Once retired, limit annual spending to 4% of your starting portfolio value, then adjust for inflation each year. The dollar amount is fixed based on year one — not recalculated as a percentage each year.

Where it came from — the original research

The 4% rule originates from a 1994 paper by financial planner William Bengen published in the Journal of Financial Planning. Bengen analyzed historical U.S. market data from 1926 to 1992 — including the Great Depression, multiple recessions, and high-inflation periods — and asked: what is the maximum withdrawal rate that would have survived every 30-year retirement period in that dataset?

His answer: 4.15%, which he rounded to 4%. The analysis assumed a portfolio of approximately 50-60% equities and 40-50% bonds, annual inflation adjustments, and a 30-year retirement horizon. The "worst case" in Bengen's dataset was a retiree who retired in 1966 — just before a brutal combination of poor equity returns and high inflation. Even that scenario survived at 4%.

The rule was later validated by the "Trinity Study" — research by three professors from Trinity University published in 1998 — which examined similar questions using portfolio success rates rather than worst-case scenarios. Their findings were consistent with Bengen's, and the 4% figure became the standard benchmark in retirement planning.

The 2026 update — what's changed

The 4% rule is being actively debated and refined in 2026, with two prominent researchers arriving at different conclusions from different directions:

Morningstar's 2026 State of Retirement Income report puts the baseline safe withdrawal rate at 3.9% for retirees using a fixed spending strategy with a 90% probability of funds remaining after 30 years. This is up from 3.7% in 2024, primarily because higher bond yields have improved fixed-income return expectations. Retirees who use a flexible spending approach — adjusting withdrawals in response to market performance — may be able to withdraw as much as 5.7% annually, according to Morningstar's research. Note that Morningstar uses forward-looking capital market assumptions rather than purely historical data, which tends to produce more conservative estimates than Bengen's historical approach.

Bengen's revised estimate of ~4.7% comes from expanding beyond the original stock allocation to include small-cap value stocks. His updated analysis suggests withdrawal rates as high as ~4.7% under specific diversified allocations that include small-cap value exposure — an asset class many investors don't hold. This figure shouldn't be treated as broadly applicable without matching the specific portfolio assumptions.

The gap between 3.9% and 4.7% isn't a contradiction — it reflects different methods and assumptions:

For practical purposes: the difference between 3.9% and 4% is $1,000/year on a $1 million portfolio — a minor calibration, not a retirement crisis. The more significant revision is for early retirees with 40-60 year horizons, where the research consistently points to 3.0-3.5% as a more appropriate withdrawal rate.

How it applies to FIRE vs traditional retirement

The 4% rule was designed for a 30-year retirement — roughly age 65 to 95. For FIRE investors retiring at 35, 40, or 45, the math changes significantly.

Extensions of Bengen-style analysis suggest a ~4% withdrawal rate has roughly an 85–90% success rate over 50-year periods, depending on assumptions — meaning potentially a 1-in-10 or higher chance of running out of money for someone retiring at 35 and living to 85. At 3.5%, the success rate climbs above 95% for 50-year windows in most extended historical analyses.

The rule of thumb for FIRE:

• Traditional retirement (30-year horizon): 3.9-4% — Morningstar's current research range is reasonable
• Early retirement (40-year horizon): 3.5% is a more conservative starting point
• Very early retirement (50+ year horizon): 3.0-3.25% with dynamic adjustments provides significantly higher confidence
• Coast FIRE or with Social Security/pension: Higher rates become more defensible when non-portfolio income covers part of expenses, reducing the required withdrawal from investments

How to use the rule correctly

The 4% rule is a starting framework, not a rigid law. Here's how to apply it correctly:

1. Use it for the accumulation target, not the withdrawal calculation. The 25x rule is the most reliable output of this research. "I need 25x my annual expenses" is a robust planning target. The precise withdrawal rate in retirement deserves more nuanced treatment.
2. Adjust for your time horizon. Use 3.5% if you're retiring before 55. Use 3.0-3.25% if you're retiring before 45 or plan to live past 90.
3. Build in flexibility. The Morningstar flexible spending approach (5.7% for dynamic withdrawers) shows that investors willing to reduce spending in down years can sustain significantly higher withdrawal rates. A 10-15% spending reduction in bad years dramatically improves portfolio survival.
4. Account for non-portfolio income. Social Security, pension income, rental income, or part-time work all reduce the required portfolio withdrawal rate. A retiree covering $20,000/year in Social Security needs a much smaller portfolio than one relying entirely on investments.
5. Don't treat 4% as the ceiling. Bengen's revised ~4.7% and the flexible-spending 5.7% suggest 4% may be conservative for some retirees — particularly those with flexible spending or additional income sources. For some retirees, especially those with flexibility or non-portfolio income, strictly targeting 25x may be more conservative than necessary.

Alternatives to a fixed 4% withdrawal

Several dynamic withdrawal strategies have been shown to outperform fixed percentage withdrawals while maintaining similar or better portfolio survival rates:

• Guardrails method (Guyton-Klinger): Set an upper and lower withdrawal limit. If spending rises above 20% more than initial rate, cut it by 10%. If it falls below a lower threshold, increase it. For example, a retiree using a guardrails strategy might start at 5%, but reduce spending by 10% after a market decline — preserving long-term sustainability while allowing higher initial income. This flexibility allows higher initial withdrawals while protecting against sequence risk.
• Variable Percentage Withdrawal (VPW): Recalculate withdrawal as a percentage each year based on remaining portfolio value and expected remaining years. Eliminates the risk of running out entirely but creates variable income.
• Floor and ceiling: Set a minimum spending level (your floor) covered by guaranteed income (Social Security, annuity, bonds) and draw additional spending from your portfolio above that floor. This approach separates essential from discretionary spending.
• Bucket strategy: Divide your portfolio into short-term (cash, 1-3 years of expenses), medium-term (bonds, 4-10 years), and long-term (equities, 10+ years) buckets. Draw from cash first, refilling from bonds and equities as markets allow. Reduces sequence risk by ensuring you never sell equities at a loss to fund near-term expenses.

The bottom line

The 4% rule is not dead — it's being refined. Morningstar's 2026 research puts the conservative fixed-spending baseline at 3.9%, while Bengen's revised research suggests 4.7% is achievable with a diversified equity allocation. The practical difference between these figures is small for most retirees.

What matters more than the precise percentage: your time horizon, your willingness to adjust spending in down years, and whether you have non-portfolio income covering some expenses. A 35-year-old retiring with a 50-year horizon needs a more conservative rate than the original research supports. A 65-year-old with Social Security covering half their expenses can likely withdraw more than 4%.

Use 25x your annual expenses as your accumulation target. Use 3.5-4% as your starting withdrawal rate, adjusted lower for longer horizons and higher if you're willing to spend flexibly. The rule is a framework — not a guarantee.