Now that you know how much money you will need to fund your retirement, you must determine how much you have already saved for this purpose. First, list the current value of all of your retirement accounts and taxable accounts. This list should include the value of 401(k) plans, IRAs, Keogh plans, and any other savings and retirement vehicles you own. Your next challenge is to determine how much these assets will be worth when you retire, assuming that you do not make any withdrawals from these accounts. 

Using your estimate of the number of years until you retire, your estimate of the average rate of return you will receive on your investment portfolio before you retire, and your estimate of the rate of inflation before your retire, calculate the real return on your investments. Now, solve for the future value of your investments using a financial calculator. Set the present value equal to the current value of your investments; set N equal to the number of years until you retire; and set the interest rate equal to your rate of return. Then solve for the future value; the result will be an estimation of the future value of your current investments.