What percentage of your portfolio can you spend each year, on retirement?

William Bernstein states with impressive historical evidence, that if you want your retirement money to last as long as you will (and you might live a lot longer than you think) then you shouldn’t plan on withdrawing more than 4% per year.
 
He discusses this in his book, The Four Pillars of Investing, on pages 229-240.  Financial advisors purporting that you can withdraw up to 8% per year don’t know what they’re talking about.  If you tried this stunt in 1965, you would have been dumpster diving by 1977.
 
I like to call it “the 4% rule” and I plan my future investment withdrawals accordingly.
 
One of my favorite blogs outlining this with further academic support is this one:  Bylo Selhi