How many broadcast "seasons" does the anime industry divide a calendar year into?

How to get close to this number

The answer is in the word. Broadcast seasons follow the calendar seasons, and a year has four of them. Any question about how an industry divides a year is answered by the calendar unless the industry had a reason to do otherwise, and this one did not.

What makes it worth knowing is the consequence, which runs through half the anime questions on this site. Because series are commissioned in quarterly blocks, almost every anime runs to a multiple of roughly thirteen episodes — so the broadcast calendar determines episode counts across the entire medium. Knowing the four-season grid lets you estimate series lengths you have never heard of.

It also produces the industry's distinctive rhythm: a large batch of new series launching simultaneously four times a year, competing for the same attention in the same week. Western television staggers premieres across a year; this system concentrates them, which is why anime discussion is organised by season rather than by show.