You have three choices for addressing small postcards. Small postcards are 4x6, 4x9, 4.25x5.5 and 4.25x6. The shaded areas shown below are reserved for addressing purposes, the white areas can be used as desired. The examples below are based on 4.25x5.5 postcards, but the measurements indicated for addressing remain the same if you are using one of the different size postcards listed above.