That's right, 250L, not gallons. It's an old auto propane tank, it's ~85 gallons water capacity. Measures 18" diameter by 80" length. A few questions. Based on the calculator I have come up with a 20"x20"x20" fire box. Gives me %118 of the recommended firebox size, I figure a little bigger cant hurt. Will having a cube be detrimental in any way? I like that it will be an inch wider to either side than the tank, has a nice symmetry. And being a cube pleases me as well, but most/all the builds I've seen on here were not cubes. Do you think there would be room for a 2nd cook rack in a tank of this diameter? I'm not really thinking it's likely, but maybe a removable one for some low profile eats, like ribs or something. Pretty stoked to get going on this. I will have the tank the weekend of July 6th, so will get to work on the fire box and rough in the legs, wheels, etc. So when the tank arrives most everything else will be done. That's the plan anyhow, and we all know that no plan survives first contact... haha Have my first BBQ contest Aug 10/11 and need a bigger rig if I want to compete in more than 1 event. So the clock is ticking. Will need to build it, test it, and learn it before then. Lots of time, right? ha!