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The 4% Rule Is Wrong (Here's What to Use Instead)

The 4% rule is simple: withdraw 4% of your portfolio in year one, adjust for inflation each year, and you won't run out of money for 30 years.

It's also dangerously misleading.

Where the 4% Rule Came From

In 1994, financial planner William Bengen analyzed historical returns going back to 1926. He found that a 4% initial withdrawal rate survived every 30-year period in his dataset.

The study was groundbreaking. But it was also backward-looking, US-only, and based on a specific bond/stock allocation.

The Three Problems With the 4% Rule

Problem 1: It gives you a single number, not a probability

The 4% rule says "this worked historically." It doesn't tell you the odds it will work for your retirement.

A Monte Carlo simulation might show that 4% has an 87% success rate given current market assumptions. That's useful information. "It worked before" is not.

Problem 2: Historical returns may not repeat

The 4% rule was tested on a period that included:

• Post-WWII economic boom
• 1980s-90s bull market
• Falling interest rates from 15% to near zero

BlackRock now projects 6.5% stock returns going forward, not the 10% historical average. Vanguard projects 4-6%. If they're right, historical safe withdrawal rates don't apply.

Problem 3: It ignores sequence of returns risk

Two retirees can have identical average returns and completely different outcomes. If your portfolio drops 30% in year one of retirement, a 4% withdrawal becomes a 5.7% withdrawal from your reduced balance.

The 4% rule assumes average returns. Retirement happens in specific sequences.

What to Use Instead

Probability-based planning with Monte Carlo simulation.

Instead of asking "did this work before?" ask "what are the odds this works given realistic assumptions?"

A Monte Carlo simulation runs thousands of possible market scenarios—good years, bad years, crashes, recoveries—and tells you what percentage of those scenarios leave you with money at the end.

This gives you:

• A success probability (e.g., 87% chance of not running out)
• Range of outcomes (best case, worst case, median)
• Ability to test different withdrawal rates and see the tradeoff

Example:

Withdrawal Rate	Success Probability
3.0%	97%
3.5%	93%
4.0%	87%
4.5%	78%
5.0%	67%

Now you can make an informed decision. Maybe 87% is acceptable to you. Maybe you want 95%+ and will withdraw less. The point is you know the odds.

The Bottom Line

The 4% rule isn't useless—it's a reasonable starting point. But treating it as a guarantee is a mistake.

Your retirement plan deserves better than "this worked for people who retired in 1966." It deserves a probability.

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