12 Heavenly Stems: Clarifying the Count and Common Misnomer

The term 十二天干 is a common misnomer that combines the word for twelve with the word for the ten Heavenly Stems. In the standard system of Chinese calendrical and metaphysical notation, there are exactly ten Heavenly Stems, or 天干, and twelve Earthly Branches, or 地支. There is no eleventh or twelfth Heavenly Stem. The confusion arises because the two sets are routinely paired, and because both are part of the sexagenary cycle known as 六十甲子. In strict technical usage, one should say 十天干 and 十二地支.

天干十个，地支十二个

The ten Heavenly Stems are 甲、乙、丙、丁、戊、己、庚、辛、壬、癸. The twelve Earthly Branches are 子、丑、寅、卯、辰、巳、午、未、申、酉、戌、亥. These two lists are closed: the Stems end at 癸, and the Branches end at 亥. There is no 第十一个天干 or 第十二个天干. When a source mentions 十二天干, it is almost always either a slip of terminology or a search phrase used by someone who has conflated the Stems with the Branches.

The distinction matters because the Stems and Branches perform different roles in the construction of the sexagenary cycle and in the analysis of a Four Pillars chart, or 四柱. A Four Pillars chart contains a year pillar, month pillar, day pillar, and hour pillar. Each pillar is written as a Heavenly Stem above an Earthly Branch. The upper character is always one of the ten Stems; the lower character is always one of the twelve Branches. No pillar is written with two Stems or two Branches.

为什么一边是十、一边是十二

The Heavenly Stems number ten because they are built from the Five Phases, or 五行, each divided into a yang and a yin form. The pairing is as follows: 甲 and 乙 belong to Wood, 丙 and 丁 belong to Fire, 戊 and 己 belong to Earth, 庚 and 辛 belong to Metal, and 壬 and 癸 belong to Water. Within each pair, the first Stem is yang and the second is yin. Thus 甲 is yang Wood and 乙 is yin Wood; 丙 is yang Fire and 丁 is yin Fire; and so on through the ten. This gives exactly ten Stems, with no need for an eleventh or twelfth.

The Earthly Branches number twelve because they correspond to the twelve months of the year and the twelve double-hours of the day. They also correspond to the twelve zodiac animals. The Branch 子 is associated with the Rat, 丑 with the Ox, 寅 with the Tiger, 卯 with the Rabbit, 辰 with the Dragon, 巳 with the Snake, 午 with the Horse, 未 with the Goat, 申 with the Monkey, 酉 with the Rooster, 戌 with the Dog, and 亥 with the Pig. The twelvefold structure comes from the division of the solar year and the daily cycle, not from the Five Phases.

Because the Stems are ten and the Branches are twelve, their least common multiple is sixty. But the cycle does not simply run through every possible combination of ten and twelve. It is further restricted by parity: a yang Stem only pairs with a yang Branch, and a yin Stem only pairs with a yin Branch. This produces sixty valid pairs, known collectively as 六十甲子. The sequence begins with 甲子 and continues through 乙丑，丙寅, and so on, until it returns to 甲子 after sixty steps. A pair such as 甲丑 never appears, because 甲 is yang and 丑 is yin.

搜「十二天干」的人通常想找的是哪一个

When someone searches for 十二天干, the intended object is usually the twelve Earthly Branches, not an imagined set of twelve Heavenly Stems. They may be looking for the twelve animals of the zodiac, the twelve months, or the twelve time periods of the day. In each case the correct term is 地支, or, more fully, 十二地支.

Alternatively, the searcher may be trying to recall the beginning of the sexagenary cycle. The first pair in the cycle is 甲子, and the cycle is sometimes loosely described as the sixty Stem-Branch combinations. A person who remembers that the cycle has sixty terms and that the Branches run to twelve may incorrectly transfer the number twelve onto the Stems. The correct way to express the structure is to say that the ten Stems and the twelve Branches combine to form sixty pairs.

In a smaller number of cases, the phrase 十二天干 may arise from a misreading of a chart. In a Four Pillars layout, the upper row contains the four Heavenly Stems of the year, month, day, and hour. The lower row contains the four Earthly Branches. If someone counts all eight characters and then recalls that the upper row has fewer members than the lower row, they may mistakenly conclude that the upper row has twelve items. The upper row has four Stems, drawn from a set of ten.

记混之后会算错什么

Treating an Earthly Branch as if it were a Heavenly Stem causes errors in at least two areas of chart analysis: Five Phase assignment and the Ten Gods, or 十神.

The first error concerns the Five Phases. A Heavenly Stem carries exactly one Phase. 甲 and 乙 are Wood, 丙 and 丁 are Fire, 戊 and 己 are Earth, 庚 and 辛 are Metal, and 壬 and 癸 are Water. An Earthly Branch, by contrast, may carry one, two, or three hidden Stems, each with its own Phase. For example, the Branch 寅 hides 甲，丙, and 戊, which are respectively Wood, Fire, and Earth. If one treats 寅 as a single-Phase item in the same way as a Stem, one loses the layered Phase information that the Branch is designed to encode.

The second error concerns the Ten Gods. The Ten Gods are relational categories derived from the interaction between the day Stem and every other Stem in the chart. The day Stem is called the 日主, or Day Master, and it serves as the reference point for the entire chart. The Ten Gods—such as 正官，七杀，正印，偏印，正财，偏财，食神，伤官，比肩, and 劫财—are defined by the relationship between the Day Master and another Stem, according to the Five Phases and yin-yang polarity.

An Earthly Branch does not directly correspond to a Ten God. Its Ten God significance is determined by the hidden Stems within it. If a Branch is treated as if it were a Stem, the analyst will assign a Ten God relationship to the Branch itself, rather than to the Stems concealed within it. This changes the reading of every pillar that contains a Branch with multiple hidden Stems, and it can invert the relational structure of the chart.

一句话分清干与支

The Heavenly Stems are the ten upper, single-Phase yang and yin expressions of the Five Phases; the Earthly Branches are the twelve lower, multi-layered markers of time, season, and zodiac position, each hiding one to three Stems. In a Four Pillars chart, the Stem is the external and active surface, while the Branch is the internal and stored layer. The day Stem, or 日主, is the fixed reference point for the whole chart. If the day Branch is mistaken for the Day Master, the entire set of Ten God relationships shifts, because the Ten Gods are calculated from the day Stem and from the Stems hidden inside the Branches. The simplest corrective is to remember that the upper character is always a Stem and the lower character is always a Branch; there are ten of the former and twelve of the latter.