Trinity Study

[Bernard]

According to the Trinity Study, we have about a 96% chance to a 30-year retirement without running out of money if we use the 4% rule. What I would like to know is how the numbers change when you aim for a 20-year retirement. How much can one withdraw kind-of-safely if they would want to be fairly certain that their retirement money lasts 20 years?

[thd7t]

There are a variety of online tools that can answer this for you.  cFIREsim is probably the most comprehensive and popular.  You can get very specific about the conditions.

[RWD]

There are a variety of online tools that can answer this for you.  cFIREsim is probably the most comprehensive and popular.  You can get very specific about the conditions.

Link:
http://cfiresim.com/

Max initial spending for 96% historical success rate over 20 years is 4.8% (otherwise default assumptions). To get to 100% success it drops to 4.4%.

[Trede]

You might find this Kitces report useful:
https://www.kitces.com/wp-content/uploads/2014/11/Kitces-Report-March-2012-20-Years-Of-Safe-Withdrawal-Rate-Research.pdf

Page 6 touches on your SWR adjustment with 20-year time horizon instead of 30.  He suggests you can up your SWR by 1% but should use a more conservative asset allocation.

[FIREstache]

If you have SS or a pension coming, you can also add that in those online tools as "additional income" and put the year it begins.  By having SS or pension in the future retirement years, you are able to withdraw a little more from the stache in the earlier years.

[thd7t]

Another small note about the Trinity Study is that it's based on a fixed stock/bond mix.  You can also adjust this in cFIREsim.  I think Trinity's mix is pretty conservative, but it might be better over shorter timelines.