BaZi basics: Heavenly Stems, Earthly Branches and the Four Pillars

Which eight characters make up BaZi?

BaZi is a way of recording a birth time. Instead of writing numbers such as January 1, 2000 at noon, it uses the traditional stem–branch system: two characters each for the year, month, day and hour, making eight in total.

The upper character is a Heavenly Stem and the lower one an Earthly Branch. Together they form a stem–branch pair, or pillar. The year, month, day and hour pairs make up the Four Pillars. BaZi and Four Pillars name the same chart, one by its character count and the other by its structure.

Notice the Year Pillar: although this person was born in 2000, commonly called a Dragon year, the chart shows Ji-Mao (己卯), the Rabbit. The BaZi year begins at Li Chun. In 2000, Li Chun fell on February 4, so January 1 still belongs to the previous BaZi year. Births early in the calendar year are especially easy to misclassify.

Heavenly Stems: ten counting signs with elemental associations

The ten Heavenly Stems run in this order: Jia, Yi, Bing, Ding, Wu, Ji, Geng, Xin, Ren and Gui (甲乙丙丁戊己庚辛壬癸). Think of them as an ancient sequence from one to ten, with each also assigned an element—Wood, Fire, Earth, Metal or Water—and a yin or yang polarity.

The pattern is simple: each pair of stems shares an element; the first is yang and the second yin. These images help you remember the signs. They are not conclusions about a person's character.

Earthly Branches: twelve zodiac animals and twelve double-hours

The twelve Earthly Branches are Zi, Chou, Yin, Mao, Chen, Si, Wu, Wei, Shen, You, Xu and Hai (子丑寅卯辰巳午未申酉戌亥). Their best-known associations are the zodiac animals: Zi the Rat, Chou the Ox, Yin the Tiger, and so on. The Year Branch indicates the zodiac animal. Branches also divide a day into twelve periods of two hours each.

The hours in this table use local solar time. Beijing standard time is based on 120° east longitude. The farther a birthplace lies from that meridian, the larger the longitude correction; in Urumqi, the difference can exceed two hours. Convert the time before assigning the Hour Pillar under this convention.

Pairing stems and branches: the sixty-pair cycle

Stems and branches advance together, one place at a time: Jia-Zi, Yi-Chou, Bing-Yin, Ding-Mao, and so on. The ten stems and twelve branches each restart after their own sequence ends. Only after the sixtieth pair, Gui-Hai, do they meet again at Jia-Zi. This is the sixty-pair, or sexagenary, cycle.

• Years: 2024 is Jia-Chen, 2025 Yi-Si and 2026 Bing-Wu. Sixty years earlier, 1964 was also Jia-Chen.
• Days: the same sixty-pair cycle advances one pair each day. This continuous day-counting tradition extends back more than two thousand years.
• The Chinese expression hua jia, used for a person's sixtieth year, refers to completing one full cycle.

There is no need to memorize every Month and Hour Stem. The Month Stem is derived from the Year Stem using the Five Tigers rule, and the Hour Stem from the Day Stem using the Five Rats rule. A calculator handles this; it helps simply to know how they are related.

What the Four Pillars traditionally represent

Besides recording time, each pillar is traditionally associated with an area of life, called a palace position. Common associations are shown below.

Palace positions locate a topic within the traditional framework. Interpretation also depends on the Five Elements and Ten Gods. Drawing a conclusion from one character in one pillar is a common mistake.

Start a BaZi reading with the Day Master

The key reference point is the Heavenly Stem of the Day Pillar, called the Day Master. It represents the person in the chart. In the example above, it is Wu (戊), Yang Earth, traditionally pictured as mountains or deep earth.

The other seven characters are compared with the Day Master. The same element represents peers; the element producing it represents resources and support; what it produces represents expression and talent; what it controls represents Wealth; and what controls it represents rules and pressure. These relationships form the Ten Gods. First identify the Day Master, then the relationships, and finally consider the chart's overall elemental balance.

Common questions

• How does BaZi differ from the Chinese zodiac or a sun sign? The zodiac animal uses only the Year Branch, while a sun sign is based on the birth month and day. BaZi uses all eight year, month, day and hour characters, providing a more detailed traditional framework.
• Do people with the same BaZi have the same fate? People born in the same double-hour can share a chart, while their birthplace, family, sex and experiences differ. BaZi describes a birth-time structure, not the whole person.
• Can a chart be calculated without a birth hour? The year, month and day can provide three pillars and six characters, but Hour Pillar topics remain uncertain.
• Which day applies to a birth after 11 pm? The Zi double-hour starts at 23:00. Schools differ on whether that period belongs to the current or following day, so establish the convention before calculating.