IME the drained weight is stated separately. The question then is how much weight do the dried beans gain as they soak up water?
They gain 1.5 times the dried weight. eg 100 g dried ==> 250 g cooked.
But as fuaran said, you don't want 400g of cooked beans you want however many fit in a 400g tin.
Anyway, all that is overly academic, it's a bit inefficient not to say time consuming soaking and cooking a handful of beans - cook the whole bag, fill an empty tin to give enough for the recipe, then freeze the rest.