Let's use historical data instead of back of the envelope guesswork. Over the last 40 years (1970-2010) the average S&P 500 return has been 11.61%, while infla

Let's use historical data instead of back of the envelope guesswork. Over the last 40 years (1970-2010) the average S&P 500 return has been 11.61%, while inflation has been 4.4%. Past performance not necessarily but usually predicting future performance, but, with those rates... Over the next 40 years $100k would grow to $8.1 MM in future bucks, or $1.45 MM in 2011 dollars. http://www.moneychimp.com/features/market_cagr.htm http://www.moneychimp.com/features/market_cagr.htm for returns, http://www.moneychimp.com/articles/econ/inflation_calculator.htm http://www.moneychimp.com/articles/econ/inflation_calculator... for inflation, and http://apps.finra.org/Calcs/1/Savings http://apps.finra.org/Calcs/1/Savings for savings calculations.