Sorry Wade, Can't say the exact holding capacity of the smallest one, not that much, but enough to make a kit seem more compfortable. I only use the 6 gallon carboys for secondaty fermentation, unless I'm doing an Island mist kit, then I'll stay with the 6 gallon right till bottling due to te addition of the F pack, which generally takes me over the 6+ gallon size. I got 32 bottles from my last greenapple reisling, using 2 of my 375ML bottles of reisling to top up with after rackings. We'll see how it works with these 2 I have going now.