Is the constellation calculated by birth or by birthday? If you are born, is it calculated by lunar calendar or solar calendar?

It's according to the solar calendar ~

Constellations and astrology were introduced from the west to the east ~

Gregorian calendar is the pioneering work of several ancient civilizations, and it is a measurement method to calculate the date according to the change of the relative position of the moon and the earth. The division of constellation dates is based on the astrological changes of the solar system and the whole galaxy. So constellations are calculated according to the solar calendar or Gregorian calendar.

This is based on the birthday of the solar calendar in the year when you were born ~