The rate of savings needed to fund retirement income is primarily dependent upon when you start. Needless to say, the sooner the better. Savings should be a percentage of your income above and beyond your “cash on hand”, that is set aside with each paycheck and invested. Expected rates of return, anticipated future earnings and social security all add to finding out how much will be needed for retirement and how much you specifically should be saving with each month.
I found this article from CNBC to provide an interesting breakdown of how to start calculating needed savings: