The 4% Rule: Where It Came From and Whether It Still Works
In 1998, three finance professors at Trinity University published a paper called "Retirement Savings: Choosing a Withdrawal Rate That Is Sustainable." It became the most cited piece of retirement research in history. Most people who cite it have never read it.
The actual finding: a 4% annual withdrawal from a diversified portfolio had a 95%+ success rate over 30-year periods, based on historical US market data from 1926–1995. That's it. No guarantees. No promises. A historical success rate, for a specific time horizon, in US markets.
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Use the FIRE Calculator →What the 4% rule actually means
Simple version: multiply your portfolio by 0.04. That's your annual spending budget.
- $500,000 portfolio$20,000/year$1,667/month
- $750,000 portfolio$30,000/year$2,500/month
- $1,000,000 portfolio$40,000/year$3,333/month
- $1,500,000 portfolio$60,000/year$5,000/month
- $2,000,000 portfolio$80,000/year$6,667/month
- $3,000,000 portfolio$120,000/year$10,000/month
You increase the dollar amount by inflation each year — not recalculate 4% of your remaining portfolio. This distinction matters. In a bad market year, your 4% might actually be 6% of what's left. That's fine. The math accounts for it.
When 4% is too aggressive
Three situations where you should use 3%–3.5% instead:
You're retiring before 50
The Trinity Study used 30-year windows. A 40-year-old needs 50+ years of runway. Historical success rates for 4% over 50 years drop to around 80–85%. Not terrible, but not 95%. For a 40-year retirement horizon, 3.3%–3.5% is the research-backed safe number.
You expect high inflation
The rule's historical success rate lived through 1970s stagflation — but barely. Average inflation in the test period was around 3%. If you're planning for a high-inflation environment and need full inflation adjustments every year, a lower withdrawal rate gives you more cushion.
Your portfolio is heavily in bonds
The 4% rule assumed a 50–75% stock allocation. A conservative 30% stock / 70% bond portfolio historically has lower long-term returns, which shrinks your safe withdrawal rate significantly — closer to 3%.
When 4% is too conservative
If you're retiring at 65+ with Social Security income, the 4% rule may make you die with too much money. Two factors change the math:
First, your time horizon is shorter. A 65-year-old needs 25–30 years of income, not 50. The success rate for 4.5%–5% over 25 years is historically very high.
Second, Social Security covers some expenses. If you have $3,000/month in SS benefits and only need $5,000/month total, your portfolio only needs to cover $2,000/month — meaning you can apply a higher withdrawal rate to a smaller "gap portfolio." Many 65+ retirees can safely withdraw 5%+ from their investment portfolio because SS covers the baseline.
The math behind the rule: sequence of returns risk
Here's the thing that breaks otherwise solid retirement plans: the order of market returns matters more than the average.
Say you retire with $1M and average 7% returns over 30 years. If those returns come in the order good-good-bad, you'll end up with far more money than if they come in the order bad-bad-good — even if the average is identical. Why? Because you're withdrawing money during the down years. You sell low, and those shares aren't there to benefit from the recovery.
The 4% rule's historical success rate is essentially a stress test against the worst sequence-of-returns scenarios in US history — 1929, 1966, 2000. If you could survive those, 4% worked. The risk is that future sequences might be worse, or that non-US-centric markets would show different results. The rule holds up well, but it's not a law of physics.
Withdrawal rates vs. portfolio size
Annual and monthly income at different withdrawal rates.
| Portfolio | 3% | 3.5% | 4%(classic) | 4.5% | 5% |
|---|---|---|---|---|---|
| $500k | $15,000/yr$1,250/mo | $17,500/yr$1,458/mo | $20,000/yr$1,667/mo | $22,500/yr$1,875/mo | $25,000/yr$2,083/mo |
| $750k | $22,500/yr$1,875/mo | $26,250/yr$2,188/mo | $30,000/yr$2,500/mo | $33,750/yr$2,813/mo | $37,500/yr$3,125/mo |
| $1M | $30,000/yr$2,500/mo | $35,000/yr$2,917/mo | $40,000/yr$3,333/mo | $45,000/yr$3,750/mo | $50,000/yr$4,167/mo |
| $1.5M | $45,000/yr$3,750/mo | $52,500/yr$4,375/mo | $60,000/yr$5,000/mo | $67,500/yr$5,625/mo | $75,000/yr$6,250/mo |
| $2M | $60,000/yr$5,000/mo | $70,000/yr$5,833/mo | $80,000/yr$6,667/mo | $90,000/yr$7,500/mo | $100,000/yr$8,333/mo |
| $3M | $90,000/yr$7,500/mo | $105,000/yr$8,750/mo | $120,000/yr$10,000/mo | $135,000/yr$11,250/mo | $150,000/yr$12,500/mo |
Frequently asked questions
Where did the 4% rule come from?
The Trinity Study, published in 1998 by three finance professors at Trinity University. They backtested portfolio withdrawal strategies against historical US market data from 1926 to 1995. A 4% withdrawal rate from a 50/50 stock-bond portfolio had a 95%+ success rate over 30-year periods. That's it. That's the whole origin.
Does the 4% rule account for inflation?
Yes — and this is critical. The rule means you withdraw 4% in year one, then increase that dollar amount with inflation each year. So if you start with $40,000 on a $1M portfolio and inflation runs 3%, you take $41,200 in year two. Your percentage of the remaining portfolio may be higher or lower than 4% depending on market performance.
What happens if the market crashes right after I retire?
This is sequence of returns risk — the biggest threat to the 4% rule. If the market drops 40% in your first two years of retirement and you keep withdrawing, you lock in losses and never fully recover. The Trinity Study accounts for this statistically, but individual outcomes vary. A flexible withdrawal strategy (cut spending in bad years) dramatically improves survival rates.
Is 4% still safe for early retirees?
Probably not. The Trinity Study used 30-year windows. If you retire at 40, you need your money to last 50+ years. Most researchers put the safe withdrawal rate for a 50-year horizon at 3.3%–3.5%. That's not a huge difference in percentage terms, but it means needing $1.43M instead of $1M for $50k/year in expenses — a 43% bigger portfolio.
Can I use 5% if I'm willing to adjust spending?
With a flexible strategy, yes. Research by Vanguard and others shows that dynamic withdrawal rules — spending less when your portfolio drops, more when it's up — allow higher average withdrawal rates with similar or better survival rates. The key word is flexible. If you can't cut spending in a down market, stick to 3.5%–4%.
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