The Ten Heavenly Stems Explained

The ten heavenly stems (天干) are the upper characters of every pillar. They are the "visible" part of a chart: what a pillar expresses openly. Each is the yang or yin form of one of the five elements, and each has fixed relations with the other nine.

The ten stems at a glance

Each stem has its own guide: 甲, 乙, 丙, 丁, 戊, 己, 庚, 辛, 壬, 癸.

Yang and yin pairs

The stems come in pairs of the same element. The yang member is traditionally described as outward, direct and large in scale; the yin member as inward, adaptive and fine in scale. Classical imagery makes this concrete:

• 甲 and 乙 (wood): a tall tree and a climbing vine.
• 丙 and 丁 (fire): the sun and a lamp.
• 戊 and 己 (earth): a mountain and cultivated soil.
• 庚 and 辛 (metal): raw ore or an axe, and refined jewellery.
• 壬 and 癸 (water): a river or sea, and rain or dew.

These images help explain relations. The sun (丙) warms everything indiscriminately; a lamp (丁) lights a small space and needs fuel (wood). An axe (庚) needs fire to be forged into a tool; jewellery (辛) is damaged by too much fire.

Combinations

Five pairs of stems combine (合): 甲己, 乙庚, 丙辛, 丁壬, 戊癸. In each pair the yang stem controls the yin stem of the opposite polarity — 甲 wood controls 己 earth — and the pair is said to combine into a new element: earth, metal, water, wood and fire respectively. In practice, a combination first binds the two stems, reducing their independent action. Full transformation into the new element requires strong support from the month; many combinations bind without transforming.

Clashes

Four pairs clash (冲): 甲庚, 乙辛, 丙壬, 丁癸. These are same-polarity stems in a controlling relation, seven positions apart. 戊 and 己 have no clash partner in the common list because earth sits in the centre. A clash between neighbouring stems is felt more strongly than one between the year and hour.

Stems in a chart

When reading the visible stems:

1. Name each stem's Ten God relative to the Day Master.
2. Check whether it is rooted — does a branch in the chart hide the same element? An unrooted stem is weak, however prominent it looks.
3. Check its neighbours for combinations and clashes.
4. Check revelation — a stem that also appears as a hidden stem is "revealed" (透干) and especially influential.

Stems from luck and annual pillars follow the same rules; a luck stem can combine with or clash a natal stem.

Each stem as a Day Master

When a stem is the Day Master, its classical image becomes a shorthand for the whole chart. A few typical questions practitioners ask:

These images come from the 滴天髓 and 穷通宝鉴 traditions and are teaching devices. They do not replace the strength and useful-element analysis, but they give a memorable starting point. Look up your own Day Master with the Day Master calculator, then read the matching Day Master page.

How the stems are counted

The ten stems combine with the twelve branches in a fixed order to make the sixty-pair cycle (六十甲子). Yang stems only pair with yang branches and yin stems with yin branches, which is why there are sixty pairs rather than 120. The year, month, day and hour stems are therefore not independent: once the year stem is known, the stem of each month follows a rule (甲 or 己 years start with a 丙寅 month), and once the day stem is known, the hour stems follow (甲 or 己 days start with a 甲子 hour).

Stems and the Ten Gods

Every other stem relates to the Day Master as one of the Ten Gods, determined by element and polarity. For a 甲 Day Master:

The Ten Gods calculator produces this table for any Day Master.

Transformation in more detail

Classical conditions for a stem combination to transform include: the two stems are adjacent; the month branch supports the new element; the new element is present or rooted elsewhere; and nothing clashes or controls it. Applied to the Day Master itself — for example a 丁 Day Master combining with a 壬 month stem in a wood season — a complete transformation creates a special structure called 化气格. Such charts are rare, and many apparent cases fail one of the conditions.

Stems in luck and annual pillars

Each luck pillar and each annual pillar has a stem. When that stem combines with the Day Master, practitioners note a year or decade of strong attraction or commitment; when it clashes the Day Master or a key stem, they note change. As always, the branches decide how lasting the effect is.

Learning the stems efficiently

1. Memorise the order 甲乙丙丁戊己庚辛壬癸 and the element pairs.
2. Learn the five combinations and four clashes.
3. Learn the main hidden stems of each branch, so you can see roots.
4. Practise naming Ten Gods for one Day Master at a time.

A week of short daily practice is usually enough to read stems fluently.

A worked example: reading the visible stems

Suppose a chart's four stems are 庚 (year), 丙 (month), 甲 (day — the Day Master) and 己 (hour).

• 甲 Day Master and 己 hour: a stem combination (甲己). The Day Master is bound to Direct Wealth in the hour — traditionally read as attachment to resources or later-life projects. Whether it transforms to earth depends on the month branch.
• 丙 month: Eating God for 甲. Next to 庚 in the year, 丙 controls 庚.
• 庚 year: Seven Killings for 甲. Because 丙 sits between 庚 and the Day Master, the classic pattern 食神制杀 applies — Eating God controls Seven Killings, and the pressure is managed.
• 甲 and 庚: these clash, but they are not adjacent (the month stem is between them), so the direct clash is softened.

The stems alone already tell a story: pressure from the year is managed by skill in the month, and the Day Master is bound to wealth in the hour. The branches would then confirm or modify it through roots and relations. Try the same exercise with your own chart from the hidden stems calculator, which shows stems and hidden stems with their Ten Gods.

Key points

• The ten stems are the yang and yin forms of the five elements. They are the visible part of each pillar.
• Classical images (tree and vine, sun and lamp, mountain and soil, ore and jewel, river and rain) are teaching devices for how stems interact.
• The five combinations (甲己, 乙庚, 丙辛, 丁壬, 戊癸) bind first. Transformation needs seasonal support and other conditions.
• The four clashes (甲庚, 乙辛, 丙壬, 丁癸) are strongest between adjacent stems.
• Every stem is a Ten God relative to the Day Master, set by element and polarity.
• A visible stem is reliable only when it is rooted in a branch, and a revealed hidden stem is especially influential.
• Month and hour stems follow from the year and day stems by fixed rules.
• Luck and annual stems combine with and clash natal stems in the same way.

Key terms in this article

Heavenly Stems · 天干

The ten heavenly stems — 甲乙丙丁戊己庚辛壬癸 — are the yang and yin forms of the five elements: 甲乙 wood, 丙丁 fire, 戊己 earth, 庚辛 metal, 壬癸 water. They sit on top of each pillar and represent what is visible or expressed.

Stem Combination · 天干五合

Five pairs of stems combine: 甲己 (earth), 乙庚 (metal), 丙辛 (water), 丁壬 (wood), 戊癸 (fire). Combination binds the two stems; whether they actually transform into the new element depends on the month and support, and many combinations only bind.

Stem Clash · 天干相冲

Stems seven positions apart with the same polarity clash: 甲庚, 乙辛, 丙壬, 丁癸. Earth stems 戊己 have no clash partner in the common list. A clash is a controlling relation between two visible stems.

Yin and Yang · 阴阳

Each element has a yang and a yin form. Yang stems are 甲丙戊庚壬, yin stems 乙丁己辛癸; branches alternate in the same way starting with 子 as yang. Polarity decides, for example, whether a relation is Direct or Seven Killings, and the direction of luck pillars.

Common questions

Are yang stems stronger? No. Polarity describes style; strength comes from season and roots.

Why do 戊 and 己 have no clash? In the standard list earth is central and is not paired; some texts discuss 戊己 interactions separately.

Do combinations always help? Binding can remove a useful stem as easily as an unfavourable one.

Next: earthly branches and hidden stems.