For electronic bonds in TreasuryDirect account,you can redeem a minimum of $25 or any amount above that in 1-cent increments. If you redeem only a portion of the bond’s value, you must leave at least $25 in the TreasuryDirect account. Redemptions are comprised of principal and interest. (In a partial redemption, we pay interest only on the partial amount you redeem.)
For paper bonds, there’s no general limit to the total value you may redeem in a single transaction; however, banks have varying policies on how much they will redeem in one transaction (and some banks may have a policy to not redeem savings bonds at all).
Take it to your bank.
there is a website just for that
