A web of expandable bags, a method for forming a web of expandable bags, and a method of forming an expandable bag containing a product is provided. The web of expandable bags includes a plurality of connected bags. Each bag includes a front ply and a back ply, and each bag is connected to an adjacent bag by a perforated connection. The front and back plies are joined to define a compartment that includes a first side, a second side, a third side that extends between the first side and the second side, and a bag opening that is configured to be closed. The front and back plies include a plurality of slits, and the plurality of slits are arranged in a plurality of spaced apart rows. The plurality of slits allows the compartment to expand in a direction that is perpendicular to the arrangement of the plurality of slits.