The three side sealing bag has two side seams and a top seam, and its bottom edge is composed of horizontally folded film. This kind of bag can be folded or not. When there are folds, they can stand upright on the shelf. A deformation of three side sealing bag is to realize the bottom edge originally folded by bonding, which essentially becomes a four side sealing bag.

Back sealing bag back sealing bag is also called pillow bag. The bags have back, upper and lower seams, making them have the shape of pillows. Many small food bags are often packed with pillow bags. The back seam of the pillow shaped bag forms a fish fin shaped sealing bag. In this structure, the inner layers of the film are sealed together, and the seam protrudes from the back of the sealed bag.

Another sealing form is stacking sealing, in which the inner layer on one side is bonded with the outer layer on the other side to form a flat sealing. Because the "fin" shaped seal is relatively robust, and as long as the inner layer of the packaging material is heat sealed, it is widely used. The "stacked" seal is relatively weak, and the inner and outer layers of the bag are required to be heat sealing materials, so it is not used much.