Hour-Based Qi Men: Setting the Cycle and Yin/Yang Dun

Hour-based Qi Men uses the current hour, solar term and day stem to set up a rotating chart.

1. Solar Terms and the Three Cycles

A year has 24 solar terms, each about 15 days. Each term is divided into Upper, Middle and Lower cycles of about five days each, corresponding to different cycle numbers.

For example, Winter Solstice uses cycles 1-7-4, Minor Cold 2-8-5, Major Cold 3-9-6 for Yang Dun; Summer Solstice uses 9-3-6, Minor Heat 8-2-5, Major Heat 7-1-4 for Yin Dun.

2. Split-and-Join Method

The split-and-join method sets the cycle in two steps:

• Solar term: the exact moment of the solar-term transition decides it. As soon as that moment passes, the new term's cycle numbers apply.
• Upper, Middle or Lower cycle: this comes from the day's "Fu Tou" (符頭), the most recent Jia (甲) or Ji (己) day up to and including today. If its earthly branch is Zi, Wu, Mao or You, it is the Upper cycle; Yin, Shen, Si or Hai, the Middle cycle; Chen, Xu, Chou or Wei, the Lower cycle.

So a solar term does not always start from its Upper cycle: whichever cycle the Fu Tou gives at the transition is the one used, and a term does not always last exactly fifteen days. That is what "split" and "join" refer to, and it is why no extra term has to be repeated as in the intercalation method.

This stays close to the astronomical calendar, but different software may compute the transition moment or set the cycle differently, so charts cast near a transition can differ.

3. Yang Dun Moves Forward, Yin Dun Moves Backward

After Winter Solstice, Yang energy rises — Yang Dun. The stems move forward through the palace numbers. After Summer Solstice, Yin energy rises — Yin Dun. The stems move backward.

This direction also governs how Zhi Shi Men is counted and which way the Eight Gods are laid out.

4. Zhi Fu and Zhi Shi Men

First find the ten-day head (xun shou) of the hour used for the chart: Jia Zi hides in Wu, Jia Xu in Ji, Jia Shen in Geng, Jia Wu in Xin, Jia Chen in Ren and Jia Yin in Gui. The star that originally belongs to the palace where that stem sits on the earth plate is Zhi Fu, and that palace's original door is Zhi Shi Men (if it is the Centre 5 palace, Zhi Fu is Tian Qin and Zhi Shi Men is Kun 2's Death Door).

This site uses the rotating-plate method. Zhi Fu follows the hour stem: it moves to the palace where the hour stem sits on the earth plate, and the other stars rotate with it around the eight outer palaces in their original order. Zhi Shi Men follows the hour branch: counting from the ten-day head's palace through the palace numbers (forward in Yang Dun, backward in Yin Dun) gives its palace, and the other doors rotate around the eight palaces with it. Together they form the moving axis of the chart.

Disclaimer: Many charting methods exist. This page explains the hour-based split-and-join rotating method for reference only.