18 Years’ Worth of Days The average retirement lasts for 18 years, with many lasting even longer. Will you fill your post-retirement days with purpose? Share | Related Content Social Security: By the Numbers Here are five facts about Social Security that might surprise you. When Should You Take Social Security Monthly Social Security payments differ substantially depending on when you start receiving benefits. Self-Employed Retirement Plans Estimate the maximum contribution amount for a Self-Employed 401(k), SIMPLE IRA, or SEP.