When does the Chinese zodiac year start?
Chinese New Year and Lichun
For the Chinese calendar year, the zodiac changes at Chinese New Year, the first day of the first lunar month. Some astrological traditions instead change the year at Lichun, Beginning of Spring. A birthday between the boundaries can therefore have two different year labels, each belonging to a stated convention.
The boundaries arise from different parts of timekeeping. A lunar month begins on the calendar day containing the astronomical new moon. Its first day starts at midnight in the calendar's reference time, not at the instant of conjunction. Lichun is a solar term that occurs when the Sun's apparent ecliptic longitude reaches 315°, a fixed position along its annual path. It does not depend on which lunar day contains it.
The Chinese calendar is lunisolar: its lunar months and solar terms follow different astronomical cycles. Chinese New Year therefore moves relative to Lichun from one year to the next. Neither January 1 nor a permanently fixed February date works as a universal zodiac boundary.
The 2018 boundary
In 2018, Lichun fell on February 4 and Chinese New Year on February 16. The outgoing calendar year was Ding-You, Rooster, and the incoming year was Wu-Xu, Dog. February 10 still belonged to the Rooster year in the Chinese calendar, while a Lichun-based year was already the Dog year.
The order can also reverse. In 1984, Chinese New Year fell on February 2 and Lichun on February 4. A February 3 birthday was in Jia-Zi, Rat, under the New Year convention but still in Gui-Hai, Pig, under a Lichun convention. The applicable boundary depends on the kind of year being used, not on which event comes first.
The exact Lichun time
A Lichun-based year can begin at midnight at the start of the date containing the term or at the astronomical instant itself. The date-based convention assigns the whole day to the new year. The instant-based convention keeps the preceding year until the event occurs.
In 2018, Lichun occurred on February 4 at approximately 05:28, UTC+8. At 03:00 that morning, a date-based year had already changed, while an instant-based year had not. All times in the table are UTC+8.
| Gregorian date and time | Chinese New Year boundary | Start of Lichun date | Lichun instant |
|---|---|---|---|
| February 4, 2018, 03:00 | Ding-You · Rooster | Wu-Xu · Dog | Ding-You · Rooster |
| February 4, 2018, 12:00 | Ding-You · Rooster | Wu-Xu · Dog | Wu-Xu · Dog |
| February 10, 2018, 12:00 | Ding-You · Rooster | Wu-Xu · Dog | Wu-Xu · Dog |
| February 16, 2018, 12:00 | Wu-Xu · Dog | Wu-Xu · Dog | Wu-Xu · Dog |
A date-only birth record on February 4 cannot resolve the instant-based classification when the birth time is unknown.
Reading a year label
For an ordinary birth-year zodiac or festival calendar, use the Chinese calendar year. For a Bazi chart, use its stated annual boundary. An exact-Lichun calculation requires the birth time and solar-term instant to be expressed on a common time basis, including the date if a time-zone conversion crosses midnight.
Changing the annual boundary changes the year label. It does not change the birthday's lunar month and day or move the date of Chinese New Year.