BAZI KNOWLEDGE BASE
The 24 solar terms in BaZi: order, Jie, Zhongqi and month branches
The 24 solar terms mark the Sun’s apparent yearly movement at intervals of 15° in solar longitude. In BaZi, they help place a birth within the seasonal year. Twelve Jie begin month-branch intervals; the twelve alternating Zhongqi do not begin additional months. Li Chun starts Yin month, Yu Shui remains within Yin, and Jing Zhe begins Mao.
Understand the seasonal names and check the solar position
Names such as Li Chun and Li Xia mark seasons; Xiao Man and Mang Zhong evoke agriculture, while White Dew and Frost Descends reflect weather observations. They carry traditional Chinese experience, particularly that of ancient central China, rather than promising rain, snow or frost everywhere on a particular day.
Modern terms are defined by solar longitude, with the spring equinox at 0° and successive terms 15° apart. For BaZi reading, the table starts at Li Chun, 315°, and ends at Da Han, 300°, before returning to Li Chun. This changes the table’s starting point, not the astronomical definition.
All 24 terms, longitudes and month-branch changes
A Jie row identifies the new month branch. A Zhongqi remains within the interval opened by the preceding Jie. These branches are not numbered lunar months, and solar longitude is not the geographic longitude of the birthplace.
| Solar term | Solar longitude | BaZi month role |
|---|---|---|
| Li Chun · Spring begins | 315° | Jie · begins Yin |
| Yu Shui · Rain Water | 330° | Zhongqi · no new month |
| Jing Zhe · Insects awaken | 345° | Jie · begins Mao |
| Chun Fen · Spring equinox | 0° | Zhongqi · no new month |
| Qing Ming · Clear and bright | 15° | Jie · begins Chen |
| Gu Yu · Grain Rain | 30° | Zhongqi · no new month |
| Li Xia · Summer begins | 45° | Jie · begins Si |
| Xiao Man · Grain fills | 60° | Zhongqi · no new month |
| Mang Zhong · Grain in ear | 75° | Jie · begins Wu |
| Xia Zhi · Summer solstice | 90° | Zhongqi · no new month |
| Xiao Shu · Minor Heat | 105° | Jie · begins Wei |
| Da Shu · Major Heat | 120° | Zhongqi · no new month |
| Li Qiu · Autumn begins | 135° | Jie · begins Shen |
| Chu Shu · End of Heat | 150° | Zhongqi · no new month |
| Bai Lu · White Dew | 165° | Jie · begins You |
| Qiu Fen · Autumn equinox | 180° | Zhongqi · no new month |
| Han Lu · Cold Dew | 195° | Jie · begins Xu |
| Shuang Jiang · Frost descends | 210° | Zhongqi · no new month |
| Li Dong · Winter begins | 225° | Jie · begins Hai |
| Xiao Xue · Minor Snow | 240° | Zhongqi · no new month |
| Da Xue · Major Snow | 255° | Jie · begins Zi |
| Dong Zhi · Winter solstice | 270° | Zhongqi · no new month |
| Xiao Han · Minor Cold | 285° | Jie · begins Chou |
| Da Han · Major Cold | 300° | Zhongqi · no new month |
Why twelve Jie, rather than every term, start months
From Li Chun to Jing Zhe, the Sun advances through 30° of longitude, passing Yu Shui between them. That interval is Yin month. Pairing the twenty-four stations in this way gives twelve solar-term months. Zhongqi does not mean a mediocre or unimportant kind of energy.
Zhongqi have their own calendar and seasonal roles even though they do not start another BaZi month. Some English references call Jie “minor terms” and Zhongqi “major terms.” Use the names and longitudes rather than assuming that “major” must mark the BaZi month boundary.
Why there is no permanent calendar date for a term
Solar terms recur near similar Gregorian dates, but their clock times vary by year and can fall on different local dates across time zones. Near a boundary, check the specific year and stated time zone. “Qing Ming is in early April” is only a seasonal memory aid.
Nor is each solar-term month exactly thirty 24-hour days. Apparent solar motion is not perfectly uniform, so successive Jie intervals differ in duration. Adding thirty days repeatedly from Li Chun cannot determine the month boundaries.