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? Related Content Potential Income from an IRA Estimate your monthly and annual income from various IRA types. Managing Your Lifestyle Using smart management to get more of what you want and free up assets to invest. What Is a Roth 401(k)? Roth 401(k) plans combine features of traditional 401(k) plans with those of a Roth IRA.