I'd like to have an income comparable to about $100K/yr in today's dollars (which is less than my current income level). To me, that is enough money to enjoy travel and hobbies and pay for kids if necessary, anticipating fewer expenses than I have today. I'm 39, and I'd say 55 would be a nice retirement age, at least from my profession.

So, figuring my current 401K balance (which I have been contributing to since I was 22 years old), the maximum 401K contributions allowed, an anticipated 3% rate of inflation, an anticipated 8% appreciation in my investments, and the amount my employer contributes to retirement, I figure I need to put an addition $25,000 per year into retirement savings, adjusted up annually with inflation, after max'ing out 401K at $15,500 currently.

On the other hand, probably less than 5% of people my age have this level of retirement planning, so most likely by the time I retire, social security will collapse, followed quickly by the economy and society. Tax rate will be 99% for anybody who has any money. So, I am reserving $2000/year for guns, ammunition, and survival equipment. Death may be an easier option, however.