ASSUMPTIONS: We assume you will live to age 92. Investment returns are 7% pre-retirement and 3% in retirement. Inflation is 3% and annual pay increases are 1.5%. Social Security uses the 2013 maximum benefit of $2,663 per month or $31,956 per year.

Estimating your income needs in retirement isn't an exact science. You can find experts suggesting between 50% and 100% of your pre-retirement income. Part of the huge variance is due to the variety of retirement lifestyles. Some retirees are content to stay home and tend their gardens. Others take off on that long-postponed world tour.