US all purpose flour has a density of 4.5 cups per pound (it is ground finer and is therefore incorporates more air space. That means 5 pounds of flour could take a gallon size container and then you would need to pack it some.

Granulated sugar has a density of 2.4 cups per pound. Therefore 5 pounds = 10 cups or 2.5 quart container

Granulated sugar has a density of 2.4 cups per pound. Therefore 5 pounds = 10 cups or 2.5 quart container