The Chinese system of time keeping is based on the Ganzhi system. Ganzhi is the short form for Tian Gan and Di Zhi which means Heavenly Stems and Earthly Branches.

The Chinese Solar or Xia Calendar is based on the earth’s rotation around the sun while the Chinese Lunar Calendar is based on the moon’s rotation around the earth. Many cultures including the Chinese believe that life on earth is influence by the movement of the heavenly bodies that include the sun, moon and planets such as Saturn, Jupiter, Mars, Venus, Mercury etc that ! Keeping track of their movement and their influence on mankind is not an easy task. It requires a good knowledge of astronomy and mathematics!

Many practitioners believe that the Ganzhi system is a model of this astronomical system and its influences. The outstanding feature of this system is it simplicity and that it can be understood and applied by almost anyone.

There are 10 Heavenly Stems and 12 Earthly Branches. They have either yin or yang properties as well as elemental property of the Five Elements as shown in the table below.

Stem	Status	Element		Branch	Status	Element
Jia	Yang	Wood		Zi	Yang	Water
Yi	Yin	Wood		Chou	Yin	Earth
Bing	Yang	Fire		Yin	Yang	Wood
Ding	Yin	Fire		Mao	Yin	Wood
Wu	Yang	Earth		Chen	Yang	Earth
Ji	Yin	Earth		Si	Yin	Fire
Geng	Yang	Metal		Wu	Yang	Fire
Xin	Yin	Metal		Wei	Yin	Earth
Ren	Yang	Water		Shen	Yang	Metal
Gui	Yin	Water		You	Yin	Metal
				Xu	Yang	Earth
				Hai	Yin	Water

The stems combine with the branches in a sequence shown below to form a cycle of 60 combinations known as the “60 Jia Zi”.

1 – 10	11 – 20	21 – 30	31 – 40	41 – 50	51 – 60
Jia Zi	Jia Xu	Jia Shen	Jia Wu	Jia Chen	Jia Yin
Yi Chou	Yi Hai	Yi You	Yi Wei	Yi Si	Yi Mao
Bing Yin	Bing Zi	Bing Xu	Bing Shen	Bing Wu	Bing Chen
Ding Mao	Ding Chou	Ding Hai	Ding You	Ding Wei	Ding Si
Wu Chen	Wu Yin	Wu Zi	Wu Xu	Wu Shen	Wu Wu
Ji Si	Ji Mao	Ji Chou	Ji Hai	Ji You	Ji Wei
Geng Wu	Geng Chen	Geng Yin	Geng Zi	Geng Xu	Geng Shen
Xin Wei	Xin Si	Xin Mao	Xin Chou	Xin Hai	Xin You
Ren Shen	Ren Wu	Ren Chen	Ren Yin	Ren Zi	Ren Xu
Gui You	Gui Wei	Gui Si	Gui Mao	Gui Chou	Gui Hai

This 60 Jia Zi is mapped to the year, month and day and repeated infinitely. For example the year 1924, 1984 and 2044 are all Jia Zi Year. The following years of 1925, 1985 and 2045 are all Yi Chou Year which is the next combination in the sequence.

Similarly if this month is Yi Chou, then the next month is Bing Yin which is the next combination in the sequence. The same applies to the day. If today is Jia Zi then tomorrow is Yi Chou. The cycle is repeated every 60 days. And if this bi-hour is Ding You, the next bi-hour is Wu Xu the next combination in the cycle.

This explains why in the Chinese Solar or Xia Calendar every day is represented by four Jia Zi combinations namely the Jia Zi of the year, month, day (and hour if specified).

To find out the Jia Zi combinations of any western day you can use this Ten Thousand Year Calendar.

Let me give an example of how this system is used to find a very inauspicious day called the Year Breaker. The stem branch combination for the year 2006 is Bing Xu. In the system of stems and branches, Xu clash with Chen (not covered here) and hence any Chen day in 2006 is considered inauspicious. This type of inauspicious clash is known as a Year Breaker!