There is a usefull tool on the savingsbonds.gov website called the Savings Bonds Calculator. I find it helpful in not just determining the current value of my bonds, but also in projecting when the bonds become redeemable and when the new rate will kick in. The last point is important if you're trying to maximize your return, since when you redeem your bonds before the 5 years are up, you lose the last three months of interest. Therefore, if you purchased the April I bonds, it might make sence to keep them for 9 months so that you get the 6 months of 4.4% interest and lose the 3 months of the new 2.57%.