<prompt> Human: My employer sponsored supplemental retirement information packet says to plan on needing an income equal to 85 of your pre-retirement income when retiring. How is this number derived? To me it sounds like one that someone just pulled out of a hat and said Sure, this sounds good! Right now my three biggest monthly expenses are mortgage, kids, and student loans. All of these expenses will go away before I retire. My employer has a pension, not a 401k, so that is income guaranteed for life. I am also contributing to a Roth IRA and will have a military reserve retirement as well. Between the pension 50 of final salary, military retirement 20 of whatever the active duty pay would be assuming I am mobilized once every five years, and social security fingers crossed I should meet this 85 rule with my Roth IRA being used to buy the retirement cabin on the water. I should be safe by the 85 rule, Im just confused about where it came from and if theres any validity to it.  <response>: I dont know for sure where it comes from, but it probably goes hand in hand with the 15 per year towards retirement rule, since you wouldnt be contributing that 15 any longer. 100 - 15 is 85.That being said, its a very generic rule and that doesnt account for what your expenses would actually be. 