Is styrofoam lighter in weight than cardboard?

Yes, Styrofoam is generally lighter in weight than cardboard. Styrofoam, or expanded polystyrene, is made up of 90% air, which contributes to its low density. In comparison, cardboard, while lightweight, is denser and heavier due to its fibrous composition. Thus, for equivalent sizes, Styrofoam typically weighs less than cardboard.