Series I versus Series EE

Where can I find comparisons on how Savings Bonds are doing against one another, for example, should I get Series EE or I bonds? And how long does it take for these bonds to mature or reach their face value. For example, a $100 dollar bond purchased for $50, how long until it is worth $100? A cashier at my bank told me they were now taking up to 21 years to reach face value. Is this correct?

Tom's response

My book, Savings Bond Advisor, has a complete analysis of the Series EE vs Series I question, which is too detailed for an email. The analysis suggests Series I bonds are the better investment.

Series EE bonds are purchased at one-half face value ($50 for a $100 bond) and the Treasury guarantees they will double in value in 20 years. This represents a guaranteed interest rate of 3.5% if you hold the bond for the full 20 years.

Series I bonds are purchased at face value and don't have a double-value guarantee. Each issue of I bond has a fixed base-rate and also earns the current rate of inflation, which is adjusted every six months. If these rates average more than 3.5%, an I bond will double in value in less than 20 years.