Author Topic: Understanding "How Much is TOO MUCH in your 401(k)"  (Read 1677 times)


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Understanding "How Much is TOO MUCH in your 401(k)"
« on: June 11, 2018, 03:52:49 PM »
Hey there,

I swear I have read the "Strategy 1" section of this article 6 or 7 time now, but it just isn't clicking for me... I want to use this strategy that is presented in the article, and I am trying to determine how much I need/want in my 401K before I should not have to worry about it. I make $33k annually, 27 years old, 401k acct is in VASGX, and I want to be able to spend around $25K (in today's dollars) annually after age 60. I am assuming $25k today would have a crap load of inflation over 30 years? How much should I have in my 401k, before I don't have to worry about it anymore?

Thanks for the help and instruction!


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Re: Understanding "How Much is TOO MUCH in your 401(k)"
« Reply #1 on: June 11, 2018, 04:44:03 PM »
You have to make some assumptions:
1) The real (i.e., not including inflation) return you will get on your investments.  Guess correctly and all is well.  Guess too high and you'll run out of money.  Guess too low and you'll work "too long".
2) When you will retire.  That choice may be made for you, or you may change your mind in either direction.
3) The withdrawal rate you will use (and that will work).  4% is a "not unreasonable" guess.

Given the assumptions above, divide your expected spending (in today's dollars) by the withdrawal rate.  E.g., $25K/0.04 = $625K.

Then you project how many years of some annual contribution you need until you can stop contributing and let compound growth alone take it the rest of the way.

E.g., if you
- have $10K in the account now
- expect to contribute $9K/yr
- expect to retire in 30 years
- expect to earn 5% real
then you would need to contribute for a little over 28 years.  See the 'Misc. calcs' tab of the case study spreadsheet

The picture below shows columns A-D and rows 16-23.  Entries in the green cells are numbers, except for cells
D17: =C23
D20: =30-C20

One could adjust cell C20 by hand, or use Data>What-If Analysis>Goal Seek... to set cell D23 to 625000 by changing cell C20.

Does that make sense?


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Re: Understanding "How Much is TOO MUCH in your 401(k)"
« Reply #2 on: June 12, 2018, 11:58:20 AM »
It makes more sense now, thank you!  I need to look at the spreadsheet link posted. Thank you again!