The ancient calendar of old proto Bulgarians was circular in shape, and inside the circle, there were 12 constellations, named after animals – a rooster, a dog, a boar, a mouse, a snow lion, a rabbit, a dragon, a snake, a horse, a sheep and a monkey.

The calendar was used to follow the movement of the sun but most of all of the planet of Jupiter.
The year consisted of 364 “counted” days and two “uncounted” or 365 days in all. The first “uncounted” day was the day of the winter solstice.

The day was precisely December 22, the shortest day of the year, that the ancient Bulgarians considered to be the start of the new year. This day was called by the old proto Bulgarians “zero” day, or Eni, Sur, Young year, and Surva year.

The calendar includes second “uncounted” day. It was called Behti, and was inserted once every 4 years in-between June 30 and July 1, after Midsummer day, the day of the summer solstice, known as Enyovden or Eni Setem.

The ordinary Bulgarian calendar year had 364 counted and one uncounted days – 365 in all. The leap year had 364 counted and 2 uncounted days – or 366 days.

The counted days were distributed into 52 weeks of seven days each. Sunday was the first day of the week, Wednesday – its middle, and Saturday – its end.

The year was divided by old proto Bulgarians into 4 quarters, each of them 91 days long or 13 weeks.

The first of the three months always had 31 days, and the second and third – 30 days.