What is a REASONABLE amount of formula?

Gi
Southwest Airlines says that you can bring a "reasonable" amount of formula on their flights. I have a 6 count 8 oz ready-to-feed formula pack. I'd like to get another pack (or one of those big single jugs of ready-to-feed formula) so I don't have to go out and get more formula the next day or two after landing. Is that considered okay?