Ethiopia’s calendar is neither ancient nor new because it is eternal image of tropics and sun. Therefore, it brings three categories of four years. Category A is the first year that begins a day late. Category B is the second and third years that each of them has similar beginning and ending days. Category C is the fourth year that ends by a day more. Categories A and B are subset of four years that each year has a period of 365 days. And category C is a subset of four years that has a period of 366 days.