The 4% rule: how much can you safely withdraw?

The 4% rule is the most quoted number in the whole FIRE world. It's a rough answer to a big question: how much can you pull out of your portfolio each year without running out of money? Here's where it comes from, how to use it, and — just as important — where it can let you down.

What the 4% rule actually says

The idea is simple. In your first year of retirement, you withdraw 4% of your portfolio. Every year after that, you take the same amount again but bump it up for inflation, so your spending power stays flat.

An example. Say you retire with $1,000,000. In year one you withdraw $40,000. If inflation runs 3% that year, next year you take $41,200 — not 4% of the new balance, but last year's amount plus inflation. You keep going like that, ignoring what the market does day to day.

Think of it like a tap you set once and leave alone. The rule's promise is that, historically, the tap wouldn't have run the tank dry over a long retirement.

Where it comes from: the Trinity Study

The 4% rule isn't a hunch. It comes from real research into US market history.

In the mid-1990s, financial planner William Bengen ran the numbers on how much retirees could safely withdraw. He tested every 30-year period he had data for and found that 4% survived them all — even retirees who were unlucky enough to stop working right before a crash.

Shortly after, three finance professors at Trinity University ran a similar study, now known as the Trinity Study. They looked at portfolios of stocks and bonds across many historical 30-year windows and measured how often each withdrawal rate lasted the distance. A 4% starting rate held up in the large majority of cases. That's how "4%" became the number everyone repeats.

How to use it: the 25× shortcut

Here's the part that makes the rule genuinely useful for planning.

If 4% a year is your target, then the pot you need is just your annual spending multiplied by 25. That's the same maths flipped around — because 1 divided by 0.04 equals 25.

Spend $30,000 a year? You need roughly $750,000.
Spend $40,000 a year? You need roughly $1,000,000.
Spend $60,000 a year? You need roughly $1,500,000.

That's your FIRE number — the finish line. The beauty of it is that it's built on your spending, not some income figure. Learn to live on less, and the target drops fast. Want to run your own numbers, including different withdrawal rates? Use the FIRE calculator.

The caveats — read these before you trust the number

The 4% rule is a great starting point, not a law of physics. A few honest warnings.

It was built on a 30-year retirement. The Trinity Study measured 30-year windows. If you retire at 40 and might need the money for 50 years, 4% is less certain. Many in the FIRE crowd trim to a lower rate — more on that below.

Sequence-of-returns risk is real. This is the big one. Two retirees can earn the same average return over 30 years and get completely different outcomes — purely because of when the bad years hit. A market crash in your first few years, while you're also selling to fund your life, does lasting damage. The same crash 20 years in barely matters. Averages hide this; the order of returns is what bites.

It assumes a specific mix. The classic studies used a portfolio heavy in stocks with some bonds. Hold something very different and the numbers shift.

It's US history. The research leans on a century of unusually strong US returns. The future — and other countries — may not be as kind.

Why some people use 3.5% instead

Because of those caveats, plenty of early retirees quietly aim lower — 3.5%, sometimes 3.25%. The trade-off is straightforward.

A lower rate means a bigger safety margin, especially over a long retirement. But it also means a bigger pot. Drop from 4% to 3.5% and your target jumps from 25× spending to about 29× — that's years of extra saving.

There's no single right answer. What matters is knowing the dial exists. Many retirees also stay flexible in practice: they trim spending a little in bad market years and enjoy a bit more in good ones. That flexibility does more for your odds than any single "perfect" percentage.

Frequently asked questions

Is the 4% rule still valid today? It's still a solid rule of thumb for planning. But treat it as a starting point, not a guarantee — especially given today's valuations and if your retirement runs much longer than 30 years.

Does the 4% rule include taxes? No. The withdrawal is a gross figure. If your withdrawals are taxable where you live, you need to fund that tax bill out of the same 4% — so budget for it.

What happens if the market crashes right after I retire? That's sequence-of-returns risk, and it's the rule's weak spot. A bad start hurts far more than a bad middle. Keeping a cash buffer and being willing to cut spending in down years both help a lot.

Should I use 4% or 3.5%? If you're retiring young or want to sleep easily, a lower rate buys a bigger margin — at the cost of a bigger target. There's no universally correct choice; pick the trade-off you can live with.