The value of U.S. savings bonds is determined by using the savings bond calculator on the TreasuryDirect website, reports the U.S. Department of the Treasury. The calculator can figure the present and future values of Series E, EE and I savings bonds.
To calculate the value of savings bonds, bond owners enter the denomination, series and issue dates of the bonds into the calculator, according to TreasuryDirect. By changing the date of calculation, owners can find out what bonds were worth in the past and what they are worth in the future. They can build and save an inventory of multiple savings bonds to more easily update calculations. The calculator also shows the interest the bonds accrue so owners can report interest profits to the IRS.
Series E bonds, known as defense bonds or war bonds, were replaced by EE bonds in 1980. Although they no longer earn interest, they are still redeemable, states TreasuryDirect. Series EE and I savings bonds are purchased at face value in any denomination of $25 or more up to $10,000. Older EE bonds earn variable interest rates, but EE bonds issued in May 2005 or after have fixed rates of interest. Series I savings bonds earn combined interest rates composed of a fixed rate added to an inflation rate.