Planning for Life Expectancy

One of the confusing things about planning for retirement is trying to figure out how long it will last. It's as if I was crouched at the start of a race without any idea how long the race will be. If it's going to be short, maybe I should sprint for it and not worry too much about running out of energy. But if it's going to be a marathon I'll want to nurse my resources and watch them carefully so I don't run out too soon. But getting some idea how long the race will be means figuring out my life expectancy.

30 Years is a Long Time!

Thirty years is a long time!  It’s a lot longer than the span of time between the year my parents had their first glimpse of me and the year I had children of my own.  It’s longer than the time between the year I married and the year my oldest child was married. How much my life and needs have changed over that span of time, and how much more they'll change over 30 years!
I'm a homeowner, so in 30 years a I would need:
  • At least one new roof, perhaps two.

The 80% Assumption, Maybe Not

Planning for retirement is usually over-simplified and full of bad assumptions, like this one: "Assume you will need 70%-80% of what you earned pre-retirement." Well you won't be sending your children through college and maybe you will have your mortgage paid off. And you won't have commuting costs, or still be trying to save for retirement. But on the other hand you will have much higher medical expenses, you may be sending your grandchildren through college, you may be providing financial assistance to your children or your parents.