Here is a handy list of food storage container sizes and quantities if you are trying to determine how much of a given product will fit.
1 gallon container = 7 lbs. wheat, rice or sugar
1 gallon container = 5 lbs. flour or powdered milk
1 gallon container = 4 lbs. dry macaroni
1 gallon container = 3 lbs. potato flakes, oatmeal or instant milk
5 gallon bucket = 35 lbs. wheat, beans, rice or sugar
5 gallon bucket = 25 lbs. powdered milk or flour
5 gallon bucket = 20 lbs. dry macaroni
5 gallon bucket = 15 lbs. potato flakes, oatmeal, or instant milk
55 gallon drum = 400 lbs. wheat, beans, rice, or sugar
55 gallon drum = 275 lbs. powdered milk or flour
55 gallon drum = 225 lbs. dry macaroni
55 gallon drum = 160 lbs. potato flakes, oatmeal, or instant milk