This is another hairy question in investment planning that defies easy answers.  To say that “it depends” seems to be a cop-out, but is actually an accurate answer, qualitatively speaking. Yet I think many investors would like quantitative answers, even if this requires making certain assumptions. This is what I plan to do in this blog.

The reason why there isn’t a single right answer to the “how long” question is because many factors determine investment wealth.  The careful reader of my last blog would have picked up some of these factors, but here is a recap:

My last blog employs simulations in Excel to project retirement shortfall risk. The example assumes that a 30-year investor (John) is investing to build a retirement fund that is sufficient to last him 25 years (from age 65 to