The 25x Expenses Rule of Thumb

The 25x rule of thumb says your retirement target should be about 25 times your annual expenses. It sounds like a separate shortcut, but it's really just the 4% rule flipped around: instead of starting with a portfolio size and asking what it can support, it starts with your expenses and works backward to the portfolio size needed to support them.

The connection is simple division. If 4% of a portfolio is a safe first-year withdrawal, then the portfolio itself must be the reciprocal of that rate, expenses divided by the withdrawal rate, which works out to exactly 25 times expenses.

Here's the math laid out directly: dividing 1 by the withdrawal rate of 0.04 gives 25. That's the whole basis of the 25x shortcut — no separate theory required, just the 4% rule rearranged into a form that's easier to use when you're starting from expenses instead of a portfolio balance.

1 / 0.04  =  25

So:  Withdrawal rate of 4%  <->  Target of 25x annual expenses

Both describe the exact same relationship between a portfolio and what it can support.

The 25x rule comes from dividing 1 by the withdrawal rate: 1 divided by 0.04 equals ____.

How is the 25x expenses rule of thumb mathematically related to the 4% rule?

This reciprocal relationship is genuinely useful, not just a math curiosity. If you already know your annual expenses, multiplying by 25 gets you straight to a target number, without needing to think in withdrawal percentages at all. The next lesson works through exactly that, starting from a real annual expense figure.

The 25x expenses rule of thumb and the 4% safe withdrawal rate describe two different, unrelated ways of estimating a retirement target.