18 Years Worth of Days The average retirement lasts for 18 years. Are you prepared to fill that many days? Share | Related Content Women and Retirement Women must be ready to spend, on average, more years in retirement than men. Immediate vs. Deferred Annuities Looking forward to retirement? It's critical to understand the difference between immediate and deferred annuities. Retirement Plan Distributions There are a number of ways to withdraw money from a qualified retirement plan.