According to the International Classification of Headache Disorders, TTHs fall into three categories:Infrequent episodic TTH: occurs once or less often per month, on average.Frequent episodic TTH: occurs 2–14 times per month, on average.Chronic TTH: occurs 15 or more times per month, for at least 3 months.
I like the fact that they added the classifications into the article. I personally wouldn't know which one to even classify myself in. Some months are worse than others, so I could range between frequent episodic and chronic. There are also outside factors that can cause headaches or migraines for me personally.