Here is what I found...
If you're interested in finding out what interest rate your Series I bonds are earning right now, use this
Savings Bond Calculator . It will give you both the current rate and current value of your Savings Bonds.
However, if the rate isn't what you expected, read on - most investors in Series I Savings Bonds have only a murky idea about how I bond rates work. Every Series I bond's rate not only changes every six months, but can swing widely between an eye-poppingly high rate and zero. Here's why:
Series I interest rates are made up of two components that are added together, a fixed rate component and an inflation rate component.
Fixed rate component
All I bonds issued within the same standard six-month window (either November-April or May-October) have the same fixed rate component.
Once a bond is issued, the fixed rate will never change for that I bond. The fixed rate is good until the bond stops paying interest 30 years later.
However, while the fixed rate on a bond that has been issued never changes, the Treasury does announce a new fixed rate for new I bonds each May and November.
The fixed rate component that the Treasury has assigned to Series I bonds at issue has ranged from a low of 1.00% to a high of 3.60%.