How is a person's zodiac and constellation determined?

The zodiac is based on your year of birth.

The zodiac sign is 12, 1.

For example, 1990 is the year of the horse.

It will be 12 years, and 2002 will be 1 year of the horse.

The constellation is your birth month.

Constellations are calculated according to the Gregorian calendar.

For example, June of Gregorian calendar 13.

Then this day is Gemini.