If you buy the large tub of popcorn at the movie theater for the free refills, go for it, tubby. But if you’re buying it because you just want the biggest size available, UC Irvine professor and author Richard McKenzie says to watch out if the medium is a bag while the large is a tub:
If you’re in a cinema which gives you a choice between buying a medium bag of popcorn and a large tub of popcorn, there’s a greater-than-50% chance that the medium bag will actually contain more popcorn than the large tub.
Here’s more of Professor McKenzie’s thoughts on popcorn economics:
The prospects of getting more popcorn in the medium than the large is higher here, since the medium is a bag with flexible sides and the tub has rigged sides. Both mediums and large sizes in Winston-Salem are bags with flexible sizes. There I always got more in the large (not much more!). Here, a little more than half the time I got more in the medium. It all depends on the clerks, and how she/he holds the bags and then chooses to literally stuff the bags by pressing the popcorn down. But then the ounce measures are not a firm indicator of value, since a higher weight can mean more bottom of the popping cabinet crumbs and un-popped kernels.