I use 2 pea sized pieces (do not grind them) and it fills the crucible about halfway
Those are some big peas :lol5:. How much you use is personal choice according to bag size, number of bags and users, etc., but your warning about not grinding is worth repeating. Not only is it totally unnessary to grind for the herbalAire (it's extremely efficient at penetrating and vaporizing the bud), it's better to use pieces so that no finely ground herb gets either down below the heating chamber or up into or past the screen.