The question is very complex and nuanced. We have to take into account many factors, such as how much you can save before retirement, inflation and market forces, how you allocate your capital and also your lifestyle and yearly expenses.
Things will look very different in all of the following situations:
This tool should help you understand how much you need to save before retirement. As we've said, depending on many different factors the number can differ widely.
That doesn't mean you shouldn't plan for it though. Another important tool to do it is the Compound Savings Calculator. It will help you figure out if and how you can hit your retirement savings target.