A flexible intermediate bulk container (FIBC) or bulk bag, or big 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 polyethylene or polypropylene, either coated or uncoated, and normally measure around 110 cm or 45-48 inches in diameter and varies in height from 100 cm up to 200 cm or 35 to 80 inches. Its capacity is normally around 1000 kg or 2000 lbs, but the larger units can store even more. A bulk bag designed to transport one metric ton of material, will itself only weigh 5-7 lbs.

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.