[miguelrochefort]

x: How much do you need to live for a year?

y: How much do you need to retire forever?

    y = 25x

[amdavidson]

Why do you assume no returns in those 25 years of retirement?

[MagnumOpus]

He does. He says "forever" not 25 years.

(Research has shown that 4% drawdown of your wealth every year combined with an investment into stocks (assets with 3.5-4% post-inflation return) will generally preserve your capital stock - and even in the worst cases won't completely erode it.

100%/4% = 25

[xchaotic]

That assumes that you'll live until 90. What if you live longer?

[miguelrochefort]

This works if you retire at 20 and live to 100.

Withdraw 4% every year and you can live on your investments forever.