A flexible intermediate bulk container (FIBC), jumbo, bulk bag, super sack, big bag, or tonne bag is an industrial container made of flexible fabric that is designed for storing and transporting dry, flowable products, such as sand, fertilizer, and granules of plastic.

FIBCs are most often made of thick woven strands of oriented polypropylene, either coated or uncoated, and normally measure around 45–48 inches (114–122 cm) in diameter and varies in height from 100 to 200 cm (39 to 79 inches). Its capacity is normally around 1,000 kg or 2,200 lb, but the larger units can store even more. A FIBC designed to transport one metric ton (0.98 long tons; 1.1 short tons) of material will itself only weigh 5–7 lb (2.3–3.2 kg).

Transporting and loading is done on either pallets or by lifting it from the loops. Bags are made with either one, two or four lifting loops. The single loop bag is suitable for one man operation as there is no need for a second man to put the loops on the loader hook. Emptying is made easy by a special opening in the bottom such as a discharge spout, of which there are several options, or by simply cutting it open.