There is disclosed a bag for the transport and storage of bulk goods or liquids formed by the assembly of several double-thickness pieces of fabric, including first and second pieces of fabric, each having opposite first and second sides extending between first and second folded-in flattened edges. Each piece of fabric includes at least one gusset defined by a first oblique section extending between the first folded-in flattened edge and a first gusset end positioned on the second side of the piece of fabric and a second gusset end positioned on the first side of the piece of fabric. The first and second pieces of fabric are assembled such that the second side of the second piece of fabric is in contact with or close to the first side of the first piece of fabric such that the first and second gusset ends of the first and second pieces of fabric are substantially aligned. The first and second pieces of fabric are assembled by means of seams formed around or near the first and second gusset ends of the first and second pieces of fabric.