[frankbreetz]

Seems like a better plan then deciding when I am going to die. What if I plan on living to my 80s, but make it to my 100s?

[nradov]

If you have accurate records for several ancestors who died of natural causes then you can put a reasonable upper bound on your lifespan. Do you have anyone in the previous few generations who lived to near 100? Lifespans haven't increased much for people who make it to adulthood.

[cma]

Plan on 100s or buy an annuity