It kind of depends on how high you heap it--some stuff will heap pretty well, other stuff won't. I had a 60" bucket on my 2250; I think I once calculated that it would hold somewhere between a quarter and a third of a yard, or about 7 tor 9 cu feet.
/ help help i need to know how many cf or yards are in a LA480 bucket
Depending on how critical/fussy you need the measurements, i.e. if you're mixing cement or such.
Fill it using a 20 liter pail, each pail is .02616 cu yd. or .7063 cu ft.