The 4% rule is the most famous number in retirement planning, and it answers the scariest question: once you stop working, how much can you pull from your savings each year without running out? The short answer the rule gives is 4% of your starting balance, adjusted for inflation - a figure with real research behind it and real limits worth understanding.
It’s a guideline, not a guarantee, and it’s widely misunderstood. Plenty of people think it means “withdraw 4% of whatever my balance is each year,” which is not what the research found. Get the mechanics right and it’s a genuinely useful anchor. Get them wrong and you’ll either overspend or scare yourself into never retiring.
Here’s where the rule came from, exactly how the math works in both directions, and the honest caveats before you build a plan on it.
Where the 4% rule came from
In 1994, a financial planner named William Bengen ran a careful study, published in the Journal of Financial Planning. He looked at every 30-year retirement window in US market history going back to 1926 - including retirees who started right before the Great Depression and the brutal 1970s inflation - and asked: what’s the highest starting withdrawal rate that would have survived even the worst of them?
His answer was about 4%. A retiree who withdrew 4% of their portfolio in the first year, then adjusted that dollar amount for inflation each year after, would have made their money last at least 30 years in every historical period he tested - even the ugliest starting points. He assumed a portfolio split between US stocks and bonds (roughly half to three-quarters in stocks).
In 1998, three professors at Trinity University ran similar research - now known as the Trinity Study - and reached comparable conclusions, which is how the “4% rule” became a household phrase. Two independent studies, decades of real market data, one durable rule of thumb.
How the math actually works
This is the part people get wrong, so read it slowly. The 4% rule sets your withdrawal in year one, then adjusts that dollar figure for inflation - it does not mean taking 4% of your current balance every year.
Here’s a $1,000,000 portfolio worked through (illustrative):
- Year 1: withdraw 4% of $1,000,000 = $40,000.
- Year 2: inflation ran 3%, so you raise last year’s withdrawal by 3%: $40,000 x 1.03 = $41,200. You take $41,200 whether the market went up or down.
- Year 3: raise again for inflation: $41,200 x 1.03 = $42,436.
Notice what’s anchored and what floats. Your withdrawal is anchored to that first-year amount and climbs with inflation, so your spending power stays roughly steady. Your portfolio balance floats with the market. The rule’s whole job is to set a spending level that history suggests the portfolio can support for 30 years, so you don’t have to cut your lifestyle every time the market dips.
The 25x flip: turning it into a savings target
The 4% rule runs in reverse too, and that’s where it becomes a goal-setting tool. If you can safely withdraw 4% a year, then the portfolio you need is 25 times your desired annual withdrawal - because 1 divided by 0.04 equals 25.
- Want $40,000 a year from savings? $40,000 x 25 = $1,000,000.
- Want $50,000 a year? $50,000 x 25 = $1,250,000.
- Want $80,000 a year? $80,000 x 25 = $2,000,000.
This is the “25x rule,” and it’s the single most useful shortcut for setting a retirement target. Remember to apply it only to the amount your own savings must cover - after subtracting Social Security, a pension, or other income. Our full guide on how much you need to retire walks through that subtraction, and the retirement calculator does the arithmetic for your numbers.
What the rule gets right
The 4% rule has survived 30 years of scrutiny for good reasons:
- It’s grounded in real history, not optimism. It was stress-tested against the worst US retirement start dates on record, including market crashes and high inflation.
- It’s simple enough to actually use. One number sets both your safe spending level and your savings target. Simple rules get followed; complex ones get abandoned.
- It builds in inflation. By raising the withdrawal each year, it protects your real spending power - a detail many homemade plans forget.
For most people planning a roughly 30-year retirement, it’s a sound starting point that turns a terrifying open question into a concrete number.
Sequence-of-returns risk in plain English
This is the risk most likely to break an otherwise sensible 4% plan, and it has an intimidating name hiding a simple idea: when you’re spending from a portfolio, the order of your returns matters, not just the average.
While you’re still working and saving, order is irrelevant. A 30% gain and a 30% drop leave you in the same place no matter which one lands first, because you aren’t pulling money out. Once you retire and start withdrawing, that stops being true. A drop early on forces you to sell more shares to raise the same cash, and those sold shares aren’t there to recover when the market bounces back.
An example makes it concrete. Two retirees each start with $1,000,000 and withdraw $50,000 at the end of every year. Both live through the exact same three yearly returns - a 30% drop, a flat year, and a 30% gain - just in opposite order (apply each year’s return, then take the withdrawal):
| End of year | Retiree A (returns: -30%, 0%, +30%) | Retiree B (returns: +30%, 0%, -30%) |
|---|---|---|
| Start | $1,000,000 | $1,000,000 |
| Year 1 | $650,000 | $1,250,000 |
| Year 2 | $600,000 | $1,200,000 |
| Year 3 | $730,000 | $790,000 |
Same starting balance, same withdrawals, identical average return - yet a $60,000 gap after only three years, purely because Retiree A met the bad year first. Strip out the withdrawals and both portfolios land at exactly $910,000; it’s the spending during the downturn that splits them apart. Stretch this over a real 30-year retirement and the divergence grows far wider - a rough first decade is often what separates “the money lasted” from “the money ran out.”
That’s why the rule’s defenders stress flexibility: skip the inflation raise or trim spending in a bad early year, and keep a cushion of safer assets so you’re never forced to sell stocks at the bottom. You can’t control the order the market deals you, but you can control how hard you lean on the portfolio while it’s down.
The honest caveats
The 4% rule is a guideline, not a law of nature. Take it seriously, but know its limits:
- It was built for a 30-year retirement. If you retire early and need the money to last 40 or 50 years, 4% may be too high - early retirees often plan around 3% to 3.5% instead.
- The future may not match the past. The rule rests on historical US returns. Morningstar, using forward-looking projections instead of history, put the safe starting rate at 3.9% for 2026 - a notch below 4%, reflecting today’s valuations and bond yields (its figure was 3.7% a year earlier). Pulling the other way, Bengen himself raised his own number to 4.7% in 2025 after modeling a more diversified mix of assets. Reasonable experts land on both sides of 4% - which tells you to treat it as a center of gravity, not a precise line.
- Sequence-of-returns risk is real. A market drop in your first few retirement years does far more damage than the same drop later - it’s the single biggest threat to a 4% plan (the worked example above shows exactly why).
- It assumes you don’t panic. The rule only works if you hold your investment mix through downturns instead of selling at the bottom. Behavior, not the formula, is usually what breaks a retirement plan.
- Returns are not guaranteed. No withdrawal rate is truly “safe.” The 4% rule improves your odds based on history; it does not remove the risk.
How to use it in practice
Treat the 4% rule as an anchor, then add a little flexibility:
- Use 25x to set your target while you’re still saving. It gives you a concrete finish line. Feed it consistently - capture every employer 401(k) match and use tax-advantaged accounts like a 401(k) or IRA to get there faster.
- Consider starting a touch below 4% - say 3.5% - if you’re retiring early or want extra safety margin.
- Stay flexible in retirement. In a bad market year, skipping the inflation raise or trimming spending a little dramatically improves how long the money lasts.
- Revisit yearly. A retirement plan is a living thing, not a set-and-forget calculation. Check in, adjust, and keep your investment mix steady.
See how your savings grow toward the target over time with our compound interest calculator.
FAQ
Does the 4% rule mean 4% of my balance every year?
No - this is the most common misunderstanding. It means 4% of your starting balance in year one, then that same dollar amount raised for inflation each year after. Your withdrawal is anchored to the first year plus inflation; it does not reset to 4% of the current balance annually.
Is the 4% rule still safe today?
It’s still a reasonable center-of-gravity for a 30-year retirement, but the experts have spread out around it. Morningstar’s 2026 research puts the cautious end at 3.9%, citing today’s valuations and yields; meanwhile the rule’s own creator, William Bengen, raised his estimate to 4.7% in 2025 using a more diversified portfolio. The honest takeaway: use 4% as a starting anchor, lean lower if you’re retiring early or want extra safety margin, and stay flexible either way.
What’s the difference between the 4% rule and the 25x rule?
They’re the same idea from two directions. The 4% rule tells you how much to withdraw from a portfolio you already have. The 25x rule tells you how big a portfolio you need to fund a target income (multiply desired annual spending by 25). One is for spending, one is for saving.
What happens if the market crashes right after I retire?
That’s sequence-of-returns risk, the 4% rule’s biggest vulnerability. A crash in your first few retirement years hurts more than a later one, because you’re withdrawing while investments are down. The common defense is flexibility - trimming spending or skipping the inflation raise in bad early years - plus keeping some safer assets to avoid selling stocks at the bottom.
Sources
- William Bengen, “Determining Withdrawal Rates Using Historical Data,” Journal of Financial Planning (1994) - the original 4% rule research, based on US market data since 1926
- Cooley, Hubbard, and Walz (Trinity University, 1998) - the “Trinity Study” that confirmed and popularized the rule
- William Bengen, “A Richer Retirement: Supercharging the 4% Rule to Spend More and Enjoy More” (Wiley, 2025) - Bengen’s own update raising the starting rate to 4.7%, using a more diversified, seven-asset-class portfolio (figure confirmed July 4, 2026)
- Morningstar, “The State of Retirement Income: 2025 Edition” (published December 3, 2025) - sets a 3.9% safe starting withdrawal rate for 2026 (up from 3.7% the prior year), assuming a 90% success rate over a 30-year retirement with a 30-50% equity allocation (figure confirmed July 4, 2026)
- The portfolio, withdrawal, and inflation figures above are illustrative; investment returns are not guaranteed and no withdrawal rate is risk-free
- Last reviewed July 4, 2026. This guide is general education, not personalized financial advice.
