A ten-label calendar series
Tiāngān (天干) comprises Jia 甲, Yi 乙, Bing 丙, Ding 丁, Wu 戊, Ji 己, Geng 庚, Xin 辛, Ren 壬 and Gui 癸. HKO records this ten-member series paired in order with the twelve Earthly Branches to make Gan-Zhi. The first pair is Jia-Zi; advancing both lists returns to it after sixty combinations.
In the explorer, keep the Chinese pair and its romanized name together when comparing a result with a reference table.
Hong Kong Observatory · Heavenly Stems and Earthly Branches ↗
Calculate before reading
The explorer calculates each visible pair using its declared solar-month, clock and rollover conventions. Read those settings before comparing two results.
For a Jia or Ji day, HKO’s hour table begins Zi with Jia, then Chou with Yi and Yin with Bing. Record the selected clock and day boundary so another visitor can reproduce the label.
Hong Kong Observatory · Heavenly Stems and Earthly Branches ↗
A displayed phase classification
Joey Yap’s Day Master table maps Jia/Yi to Wood, Bing/Ding to Fire, Wu/Ji to Earth, Geng/Xin to Metal and Ren/Gui to Water, each with yin or yang polarity. In this named modern practitioner framework, Bing (丙) is displayed as Yang Fire.
The Explorer uses that mapping for its visible-stem label. It does not convert it into a measured trait, a verdict about a chart, or an exhaustive BaZi reading.
Keep position in view
Choose a pillar first, then read its stem beside its branch, Chinese pair and settings. The same stem in a year pillar and an hour pillar has been calculated in different calendar roles. Follow Day Master for the special use of the day-pillar stem as an interpretive reference.
The Ten Gods inspector compares each visible stem with the Day Master using phase direction and polarity. Hidden branch stems are available in their own inspector. Strength, favorable phases and luck periods remain outside this view.
Word origin · etymology
English translation of Chinese tiāngān, 天干.
Heavenly renders tiān and stem renders gān. The plant-like English name identifies one set of the traditional stem–branch pairing.
Hong Kong Observatory: Heavenly Stems and Earthly Branches ↗
How we know · epistemology
Historical cyclical notation
The ten stems form an ordered calendar vocabulary whose sequence can be checked. Their phase and polarity correspondences are traditional classifications, not observations of ten distinct forces acting on a birth.
Hong Kong Observatory: Heavenly Stems and Earthly Branches ↗
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Mentioned in 17 other entries
These links connect subjects and terminology. They do not establish a shared historical origin.
Sources & provenance
Use the citations beside each section to distinguish a calculation convention, a historical teaching and an editorial example.