Starpath · Culture and history
The Chinese calendar
Months follow the moon; the year keeps pace with the sun.
The traditional Chinese calendar is lunisolar. Each month begins at a new moon and lasts 29 or 30 days. Twelve lunar months are shorter than a solar year, so a leap month is added roughly every three years.
The year begins at the new moon closest to the Start of Spring (立春), usually between late January and mid-February.
Zi Wei Dou Shu uses this calendar: your lunar birth month and day, and the lunar year that begins at Chinese New Year.
Go deeper
Alongside the months, the sun’s path is divided into 24 solar terms, such as the Start of Spring or the Winter Solstice. BaZi changes year at the Start of Spring, while Zi Wei Dou Shu changes at the lunar new year, so the two can disagree for people born in late January or February.
A month without one of the principal solar terms becomes the leap month. Schools treat a leap-month birth differently; Astravia lets you choose and shows which rule it used.