Each person is unique and consequently, the length of therapy depends on you and your needs, challenges, history and expectations for change. Although someone with a phobia may only need 2-3 sessions to create noticeable change; someone who suffers from anxiety may need at least 10 sessions. The more severe  your symptoms and your history of trauma, the longer the treatment.  In general short term therapy is considered 10 sessions or less. Mid-range therapy is between 10-20 sessions and long term therapy is more than 20 sessions.