For me, I can tell if it is the right dose by how I feel. I started taking 10mg of Adderall XR and it helped me but not quite as much as I would have liked. When I say it helped me I mean I was able to start to organize things, I could almost read long posts, and I could hold parts of a conversation with others. Once I was switched to the 20mg it just all fell in place. I am organized, reading posts are no longer an issue, and I can hold a full conversation without interrupting others. I am focused and the "chatter" that used to go on in my head no longer is there. I wasn't hearing voices, but you know what I mean, constant random thoughts.