I have the impression that the cans of food in the US list the quantity by weight. Unfortunately, I can't really tell, since they usually say how many ounces. But, are those fluid ounces or avoirdupois ounces? It's easy to figure out in Canada, the quantities are listed in millilitres and sometimes in litres. But, when a US recipe calls for a 15 ounce can of beans, is that nearly a pound or is it nearly a pint?