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The 4% rule says you can withdraw 4% of your portfolio in your first year of retirement, then adjust that dollar amount for inflation each year, and the money should last about 30 years. It is a useful planning guideline, not a guarantee, and very early retirees often use a more conservative 3.5%.
The 4% rule is the most cited number in retirement planning, and the backbone of the FIRE movement. It turns a scary question (“how much do I need?”) into simple math. But it comes with real caveats that matter, especially if you plan to retire early. Here is how it works, where it came from, and how to use it without over-trusting it. For the bigger picture, see our FIRE guide and the retirement accounts hub.
- The 4% rule: withdraw 4% of your starting portfolio in year one, then adjust that amount for inflation annually. It targets roughly a 30-year retirement.
- The inverse is your “number”: multiply annual expenses by 25. Spending $40,000 a year implies a $1,000,000 target.
- It came from the 1990s (Bengen and the Trinity Study) using historical US market data and a stock-and-bond portfolio. It is a guideline, not a promise.
- For 50-plus-year early retirements, many planners use 3 to 3.5%; for shorter retirements, some argue 4% is conservative.
- The biggest real-world risk is a bad market early in retirement (sequence-of-returns risk), which flexible spending can soften.
What is the 4% rule?
The 4% rule is a guideline for how much you can safely withdraw from a retirement portfolio each year without running out of money. In year one, you withdraw 4% of the portfolio’s value. In every following year, you withdraw the same dollar amount adjusted for inflation, regardless of what the market did. Historically, a portfolio of stocks and bonds following this approach lasted at least 30 years in the large majority of cases.
Example: with a $1,000,000 portfolio, you withdraw $40,000 in year one. If inflation is 3%, you withdraw $41,200 the next year, and so on. The percentage is only used once, at the start; after that you are inflation-adjusting a dollar figure, not taking 4% of a changing balance.
How do you calculate your number?
Flip the 4% rule around and it becomes a savings target: your number is roughly 25 times your annual expenses (because 1 divided by 4% equals 25). Note that it is based on expenses, not income.
| Annual expenses | Target at 4% (x25) | Target at 3.5% (x28.6) |
|---|---|---|
| $40,000 | $1,000,000 | $1,143,000 |
| $60,000 | $1,500,000 | $1,714,000 |
| $80,000 | $2,000,000 | $2,286,000 |
| $100,000 | $2,500,000 | $2,857,000 |
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Where did the 4% rule come from?
Financial planner William Bengen introduced it in 1994 after testing historical US market returns, and the 1998 Trinity Study reinforced it by analyzing stock-and-bond portfolios across many 30-year periods. Both found that a roughly 4% initial withdrawal, adjusted for inflation, survived almost every historical 30-year window with a diversified portfolio (often modeled around 50% to 75% stocks).
It is worth knowing the assumptions: US historical data, a 30-year horizon, a stock-and-bond mix, and no allowance for investment fees or taxes. Change any of those and the safe rate can move. Bengen himself later suggested the safe rate may often be higher than 4%, while other researchers have argued for lower rates in periods of high valuations. The honest takeaway is that 4% is a reasonable central estimate, not a precise law.
Why do early retirees often use 3.5%?
The original research targeted a 30-year retirement. If you retire at 45, your money may need to last 45 to 50 years, which is a tougher test. To add a margin of safety, many in the FIRE community use 3 to 3.5% instead of 4%, which raises the target multiple from 25 to roughly 28 to 33 times expenses. A lower rate means a bigger number, but more cushion against a long retirement and weak early markets.
What are the main risks to the 4% rule?
Sequence-of-returns risk is the big one: a steep market drop in the first few years of retirement, while you are withdrawing, does far more damage than the same drop later. Two retirees with identical average returns can end up very differently depending on the order those returns arrive.
Inflation, fees, and taxes also matter. High-fee funds quietly lower your safe rate, and withdrawals from pre-tax accounts are taxed. A long horizon (early retirement) and a too-conservative portfolio (too few stocks to outpace inflation over decades) both add strain. None of these break the rule; they are reasons to treat 4% as a starting point you adjust.
How can you make withdrawals safer?
- Stay flexible. Trimming withdrawals in down years (spending a bit less after a bad market) dramatically improves how long a portfolio lasts. Rigidly raising withdrawals through a crash is what gets people in trouble.
- Keep a cash buffer. One to two years of expenses in cash lets you avoid selling investments during a downturn.
- Mind fees. Low-cost index funds keep more of your return working for you.
- Layer in other income. Social Security, a pension, or part-time work reduces how much your portfolio has to carry. See how Social Security fits your plan.
Frequently Asked Questions
It remains a widely used planning guideline. Researchers debate the exact safe rate (some argue higher, some lower depending on market valuations and horizon), but 4% is still a reasonable central estimate for a roughly 30-year retirement. Treat it as a starting point you adjust for your situation, not a guarantee.
Multiply your expected annual expenses by 25. If you expect to spend $50,000 a year, the target is about $1,250,000. For a very long or early retirement, using a 3.5% rate (multiply by about 28.6) gives a larger, more conservative target.
Both describe a safe initial withdrawal rate. The 4% rule was built for a 30-year retirement; the 3.5% version adds a safety margin for longer retirements (common in early retirement), at the cost of needing a larger portfolio. Lower rate, bigger number, more cushion.
No. The original research did not subtract taxes or investment fees, so your real spendable amount depends on which accounts you draw from. Withdrawals from pre-tax accounts are taxed as income, while Roth withdrawals are generally tax-free, which is one reason tax diversification matters.
It is the risk that poor market returns early in retirement, while you are withdrawing, permanently shrink your portfolio. The same average return can produce very different outcomes depending on whether the bad years come first or last. Flexible spending and a cash buffer help manage it.
The bottom line
The 4% rule is a clear, useful starting point: save about 25 times your annual expenses, then withdraw 4% in year one and adjust for inflation. Treat it as a planning lens, lean toward 3 to 3.5% for a long early retirement, and stay flexible with spending so a bad early market does not derail you.
- Building toward early retirement? Read our FIRE movement guide.
- Want a number by age? Read how much you need to retire by age.
- Retiring before 59.5? Read our Roth conversion ladder guide for penalty-free access.
A quick note: this article is for educational purposes only and is not investment advice. The 4% rule is based on historical data and assumptions that will not repeat exactly, and past performance does not guarantee future results. Consider speaking with a qualified financial advisor about your own withdrawal plan.
