Heavenly Stems and Earthly Branches

Heavenly Stems and Earthly Branches are the basic time code behind BaZi, the Chinese zodiac, Huang Li, Chinese hours, and many traditional calendar expressions. The system combines ten stems and twelve branches into the 60 Jiazi cycle used to name years, months, days, and hours.

This matters because many popular explanations talk about the zodiac as if it were only an animal personality system. In the traditional structure, each zodiac animal is connected with an earthly branch. That branch can also point to a time of day, a month, a direction, and a place inside a birth chart.

Ten Heavenly Stems

The stems carry visible time quality through Yin, Yang, and the Five Elements. They are often read as the surface tone of a year, day, month, or hour.

Stem	Name	Yin/Yang	Element
甲	Jia	Yang	Wood
乙	Yi	Yin	Wood
丙	Bing	Yang	Fire
丁	Ding	Yin	Fire
戊	Wu	Yang	Earth
己	Ji	Yin	Earth
庚	Geng	Yang	Metal
辛	Xin	Yin	Metal
壬	Ren	Yang	Water
癸	Gui	Yin	Water

Twelve Earthly Branches

The branches carry grounded time position. They connect zodiac animals with months, Chinese hours, directions, seasonal rhythm, and chart structure.

Branch	Name	Animal	Direction
子	Zi	Rat	North
丑	Chou	Ox	Northeast
寅	Yin	Tiger	East-Northeast
卯	Mao	Rabbit	East
辰	Chen	Dragon	East-Southeast
巳	Si	Snake	South-Southeast
午	Wu	Horse	South
未	Wei	Goat	South-Southwest
申	Shen	Monkey	West-Southwest
酉	You	Rooster	West
戌	Xu	Dog	West-Northwest
亥	Hai	Pig	North-Northwest

How the 60 Jiazi cycle works

The cycle begins at Jia Zi, then advances one stem and one branch at a time. Because the stems repeat every 10 steps and the branches repeat every 12 steps, the full sequence returns after 60. Yang stems pair with Yang branches, and Yin stems pair with Yin branches, so the complete sequence contains 60 paired positions.

Step 1: Jia Zi / 甲子

Yang Wood over the Zi Rat branch. This is the opening pair of the 60-cycle.

Step 2: Yi Chou / 乙丑

The stem and branch both move forward one step while keeping Yin-Yang parity.

Step 31: Jia Wu / 甲午

The stem has returned to Jia, but the branch has moved to Wu Horse.

Step 60: Gui Hai / 癸亥

The final pair before the sequence returns to Jia Zi.

Where stems and branches appear

BaZi

A BaZi chart has four pillars: year, month, day, and hour. Each pillar is one stem-branch pair.

Chinese zodiac

The twelve zodiac animals are the most familiar names for the twelve earthly branches.

Chinese almanac

The Huang Li uses stem-branch names for years and days, then reads them beside Yi/Ji, Chong, Sha, and solar terms.

Chinese hours

Each two-hour period of the day is connected with an earthly branch, such as Zi hour, Chou hour, or Wu hour.

How to read one pair

A stem-branch pair becomes meaningful only when its position is named. A pair can be a year pillar, month pillar, day pillar, or hour pillar.

The stem gives the visible tone: element plus Yin or Yang. The branch gives the rooted time position: animal, direction, season, hour, and hidden element relationships.

In BaZi, the day stem is often treated as the reference point called the day master. But even that important point must be read with the other pillars, season, elements, hidden stems, and interactions.

In the almanac, the same time code appears in the record for a specific date. A Huang Li page may show the day pillar beside Yi/Ji, Chong, Sha, and solar terms. That dated almanac record can then be compared with a personal chart when the reader needs a more specific reading.

Common confusions

Zodiac animal versus earthly branch

The animal is the familiar name. The branch is the time position underneath it. Horse is the familiar animal; Wu is the branch.

Gregorian year versus stem-branch year

A Gregorian year begins on January 1. A Chinese zodiac or stem-branch year may use Lunar New Year or Li Chun depending on context.

Day pillar versus whole chart

The day pillar is important in BaZi because it contains the Day Master. The year, month, hour, Five Elements, hidden stems, and branch interactions complete the chart context around it.