Life expectancy is a statistical measure that estimates how long a person is expected to live. It is computed for an individual or for classes of people such as women between the ages of 35-45. The statistic can be computed by taking into account family history, physical condition, nutrition, environment, lifestyle habits such as smoking, exercise, and sleep patterns. Insurance companies use life expectancy tables to calculate your premium as well as the payout that you get from your annuity. The longer you live, the longer you’re expected to continue living. Figuring out your life expectancy will give you an idea as to how much you need in retirement savings to ensure you don’t run out of money before your death. The IRS Publication 590 is a single life expectancy table.