To clarify why the answer isn't directly here is that "it depends" on a number of factors, including how expensively you want to live after your retirement, what you expect the inflation rate to be, how much you expect your savings to earn while you are retired, and how long you expect to live. Once you know that, the calculations are possible.
The "4% Withdrawal Solution" is excessively naive, given that adding the other factors isn't that difficult. For example, using the 4% formula, with 3% inflation, the money will run out after 19 years – if you retire at 50, that's probably too soon.
The major factor remains "What does comfortable mean to you?" This depends on far too many factors to be amenable to a one size fits all solution.