I like this one from dinkytown .
It's more of a quick guess tool but it works well enough.
this one uses average returns which do not work when spending down . the exact same average return like this figures can run out of money 15 years earlier or later just based on the order the gains and losses come in . this kind of calculator never has a losing year while spending down . every year assumes the same average return .
a terrible way to guesstimate things in the real world where every year is different and sometimes with extended losing years .
you want to plan around the worst case's . not the average . it is no different than building a house to weather a storm . if i was building a home here in nyc i would construct to at least withstand sandy . then at least i am starting out with the best possible odds on my side . .
that is what real retirement claculators do . they stress test you against withstanding the likes of the person who retired in 1907,1929,1937 1965/1966 .
what they don't do is take an average return and apply it to every year with no down years in the mix . as i said above some worst case outcomes had very good markets over 30 years . but it is inflation and the sequence of those returns that crushed retirees .
the danger of using a calculator like the one above is that it is hardly ever the average returns that have killed off a failing time period . what killed every single worst case scenario has been this :
the portfolio's failed to return at least a 2% real return average over the first 15 years of a 30 year period .
everyone pretty much had decent 30 year market average returns . but the fact was inflation and the sequences of the gains and losses killed the retirement .
even the worst group ever , the 1966 retire was part of the greatest bull market in history . very good average return . but there just was not enough money left by the time the bull market arrived to grow , so they failed and did it with an average return over 30 years of 10.23% .
but what killed them was the first 15 years saw :
1966-stocks minus .13%--bonds 1.08%--rebalanced .64%-- inflation 5.38%