The internet says ("so it must be true!") that most baler chutes are 18" (high) x 18" (wide). The bale length can be adjusted but many end up being 36"-40" long.
so....
1.5' x 1.5' x 3.33' bale is 7.5 cubic feet.
So 2000 bales would be 15,000 cubic feet.
Not accounting for posts, or hay elevator space etc..
A 25' x 25' x 25' space,
or a 50' x 25' x 12' space, etc... is ~15,000 cubic feet.