Where did the 4% rule come from?

The Trinity Study (Cooley, Hubbard, and Walz, 1998) analyzed historical US market returns from 1925 to 1995. They found that a 4% withdrawal rate from a balanced stock/bond portfolio had roughly a 95% success rate over 30-year periods. The '4% rule' is shorthand for that finding, not a guarantee or a universal law.

Does the 4% rule account for inflation?

Yes. The standard version assumes you increase your withdrawal by inflation each year so your purchasing power stays constant. Start at $40,000/year with 3% inflation and you withdraw $41,200 the next year, $42,436 the year after. The growing withdrawal is what makes long timelines hard.

What is sequence-of-returns risk?

It's the risk that bad market returns early in retirement permanently damage your portfolio. If the market drops 40% in year one and you're still withdrawing, you're selling shares at low prices. Those shares never recover in your portfolio because you already spent them. Two people with identical 30-year average returns can have very different outcomes depending on whether the bad years came first or last.

Can I use a higher rate if I have other income?

Often yes. If Social Security, a pension, or rental income covers a meaningful portion of your expenses, your portfolio only needs to cover the gap. That smaller effective withdrawal rate relative to portfolio size creates a lot more room. Someone with a $1M portfolio spending $40,000/year but receiving $20,000 from Social Security is effectively withdrawing at 2%, not 4%.

Financial Decisions

Does the 4% rule work for me?

Sometimes. It depends on how long you need the money to last, how flexible your spending is, and when you happen to retire. The number is a starting point, not an answer.

What the math actually shows

1. The 4% rule was built for 30-year retirements using US historical data. It was never meant to cover every situation.
2. For longer retirements (40+ years), most research lands at 3.25–3.5% as more defensible.
3. If your spending can flex down 10–20% in bad years, higher rates often hold up. Fixed spending is the hard case.
4. Bad markets in the first 5 years of retirement matter far more than average returns over the full period.

The factors that actually change the answer

These aren't opinions. They're what the historical data shows.

Your retirement length matters more than the rule

The Trinity Study was built around 30-year retirements. If you retire at 65 and live to 95, that's what it was designed for. Retire at 45 and live to 90, and you're running a 45-year portfolio. That's a different problem. The longer your timeline, the more a fixed 4% withdrawal compounds the risk of running short.

Common trap

People apply the 4% rule regardless of age. A 40-year-old early retiree and a 65-year-old traditional retiree face very different math. The same number doesn't fit both.

What the research shows

30-year horizon: 4% has solid historical backing. 40+ years: most researchers land closer to 3.25–3.5%. Under 20 years: 4–5% is often fine.

Flexibility changes the math significantly

A fixed withdrawal strategy means you take out the same inflation-adjusted amount every year, good market or bad. If you can cut spending 10–20% in a down year, your portfolio survives scenarios that would wipe out a rigid strategy. Bad markets early in retirement are what most often kill portfolios, and the ability to spend less in those years is what most often saves them.

Common trap

The 4% rule is built around a worst-case fixed spending assumption. If your spending actually adjusts with your situation, you have more room than the number suggests.

What the research shows

If you can reduce withdrawals by even 10% in bad years, most researchers suggest you can sustain 5%+ initial rates over the long run.

What you hold matters as much as how much you withdraw

The Trinity Study tested portfolios ranging from 100% bonds to 100% stocks. Counterintuitively, 100% stocks outperformed in most scenarios, because bonds didn't provide enough growth to sustain withdrawals long-term. A heavy bond allocation in early retirement can actually increase depletion risk. Portfolio composition changes how far your money goes.

Common trap

People shift heavily into bonds at retirement because it feels safer. For a 30+ year portfolio, an overly conservative allocation can be as dangerous as withdrawing too much.

What the research shows

Most research supports 60–80% equities for the early retirement years. Shifting more conservative over time is reasonable, but not before you need the growth.

When you retire relative to the market changes everything

Retiring in 2009 (market bottom) gave you a completely different outcome than retiring in 2000 (right before a 50% crash). The first decade of retirement sets the trajectory. If the market drops 40% in year two and you're still withdrawing, your portfolio may never recover. No fixed rule fully accounts for when you happen to retire.

Common trap

The 4% rule's historical success rate includes some very lucky start years and some very unlucky ones. The average looks fine. The worst case does not.

What the research shows

If you're retiring when valuations look historically high (high CAPE ratio), some researchers suggest starting at 3–3.5% to leave a margin for a rough first decade.

Run the numbers

See how long your portfolio actually lasts

Plug in your portfolio, withdrawal rate, expected return, and inflation. The calculator shows you year-by-year whether your money runs out or grows indefinitely. Try 3%, 4%, and 5% side by side to see how much the number actually matters for your situation.

Open the Safe Withdrawal Rate Calculator

What's your situation?

Most people fall into more than one of these.

Retiring at 60–65, 30-year horizon

This is what the Trinity Study was built around. Still worth stress-testing, but the backing is solid.

4% is historically well-supported

Early retirement (40s or 50s), 40+ year horizon

A longer timeline compounds small errors. Most modern research for early retirees lands below 4%.

Consider 3.25–3.5%

Flexible spending (can cut 10–20% in bad years)

Flexibility is the biggest lever. A dynamic strategy can support a higher initial rate.

4–5% may be sustainable

Fixed expenses, pension/Social Security not covering basics

With no ability to cut spending, a conservative rate is your only buffer against bad timing.

Stay closer to 3.5%

Heavy bond allocation (50%+ bonds)

Bonds haven't kept pace with inflation well enough to sustain long withdrawals in most historical periods.

4% carries more risk than it looks

Social Security, pension, or rental income covering part of expenses

If other income covers a chunk of spending, portfolio withdrawals stay small relative to its size.

4%+ may be very comfortable

The bottom line

For someone retiring in their mid-60s with a 30-year horizon, a balanced portfolio, and some flexibility to adjust spending, 4% has historically worked well. That's what the research was built around and where its track record is strongest.

For early retirees with longer timelines, more conservative researchers now land at 3.25–3.5%. The difference between 4% and 3.5% on a $1M portfolio is $5,000/year. That's real money, but running out of it in year 35 is worse.

The rule also doesn't account for what you're holding, what else you've got coming in, or what the market looks like when you retire. Two people using the same 4% can have completely different outcomes depending on those variables.

Use 4% as a first approximation, not a final answer. Then run the actual numbers for your situation.

Tools to run the numbers

Safe Withdrawal Rate Calculator

Test any withdrawal rate against your portfolio, return assumptions, and inflation. See the year-by-year outcome.

FIRE Calculator

Find your FI number and see when you hit it based on your savings rate, current portfolio, and expenses.

Retirement Calculator

Project how your portfolio grows before retirement so you know what balance you're withdrawing from.

Compound Interest Calculator

See how returns compound over time and how inflation erodes purchasing power in parallel.

Common questions

Related decisions

Should I pay off debt or start investing?Is going back to school worth the debt?

Note

This page is for educational purposes only and is not financial advice. Historical market performance does not guarantee future results. Individual circumstances vary. Consider speaking with a licensed financial advisor before making major retirement decisions.