I dont know.
I have a Master Forge vertical which is basically a cheap WSM clone equivalent to a 18" WSM I would guess
I use Wicked Good lump, a full pan lasted me 15 hours at 225f using an Auber ATC. I think the ATC really helps in fuel comsumption
Here are some pics of the first test cook I did. This was a before and after shot of the pan. The pan was not completely full like it was for the 15 hr cook. I did some country ribs then some bacon. I set it to 160f for the bacon. I did add a few more chunks of hickory along the way,
I started it by lighting 20 briqs in a chimney and pouring them on top. I snuffed out the fire after about 8 hours and this is what was left
I am very happy using this lump anyway