To determine your total retirement needs, you can’t just estimate how much annual income you need. You also have to estimate how long you’ll be retired. Why? The longer your retirement, the more years of income you’ll need to fund it. The length of your retirement will depend partly on when you plan to retire. This important decision typically revolves around your personal goals and financial situation. For example, you may see yourself retiring at 50 to get the most out of your retirement. Maybe a booming stock market or a generous early retirement package will make that possible. Although it’s great to have the flexibility to choose when you’ll retire, it’s important to remember that retiring at 50 will end up costing you a lot more than retiring at 65.