A bulk bag or FIBC, Flexible Intermediate Bulk Container, is a large woven bag designed to carry bulk materials. Bulk bags generally come in standard size of 96 x 96 x 125 cm, (filled dimensions) and may contain up to 4000lbs of material, depending on the design. FIBCs have flexible walls, unlike RIBCs, Rigid Intermediate Bulk Containers, and tend to be used for dry bulk solids. Developments in bag liners and bulk bag manufacturing allow bulk bags to be used in other applications as well.

Use of bulk bags has been on steadily increasing. Approximately 100 million bags are used annually with an average annual growth rate of around 12% per year. This growth is projected to continue due to the many advantages bulk bags provide over other containers, like paper bags, rigid IBCs, fiber, plastic, or metal drums.