levi is right, depends on your body fat, also on scartissue, you're guaranteed to have success with 1.5" I personally rarely hit the glutes anymore....its a "pain in the ass" so to speak...to twist around aspirate and plunge for me. Quads, Lats, Pecks, Bi's tris, Delts, give ample areas that you can do sitting down....and shorter darts.