Five Tigers Method for the Month Stem
Learn the five Year-Stem groups that set the Yin-month stem, then advance through the twelve Bazi months without using a lunar-month shortcut.
Overview
The Five Tigers Method (五虎遁) derives the Month Stem from the Bazi Year Stem. Jia or Ji years begin Yin month with Bing; Yi or Geng with Wu; Bing or Xin with Geng; Ding or Ren with Ren; and Wu or Gui with Jia. From that starting stem, advance one Heavenly Stem for each successive Month Branch. The rule is applied only after the correct Li Chun year and Jie month have been established.
At a glance
- Jia or Ji year
- Bing-Yin starts the month sequence
- Yi or Geng year
- Wu-Yin starts the month sequence
- Bing or Xin year
- Geng-Yin starts the month sequence
- Ding or Ren year
- Ren-Yin starts the month sequence
- Wu or Gui year
- Jia-Yin starts the month sequence
- Prerequisite
- Correct Li Chun Year Stem and Jie Month Branch
Five Tigers supplies the stem of the Yin month
The method groups ten Year Stems into five pairs. Each pair points to one starting Heavenly Stem for the Yin month at Li Chun.
It does not identify the Month Branch. The solar-term interval must be calculated separately before the two characters are joined.
- Year Stem is the lookup key.
- Yin is the fixed starting branch.
The five mappings must remain exact
甲己之年丙作首: Jia and Ji start with Bing-Yin. 乙庚之歲戊為頭: Yi and Geng start with Wu-Yin. 丙辛歲首尋庚起: Bing and Xin start with Geng-Yin.
丁壬壬位順行流 gives Ren-Yin for Ding and Ren years; 若問戊癸何方發，甲寅之上好追求 gives Jia-Yin for Wu and Gui years.
- Preserve the five paired groups.
- Do not infer the start from element similarity.
Advance one stem for each following month branch
After selecting the Yin-month stem, the stem sequence continues cyclically through the ten Heavenly Stems as the branch advances through Mao, Chen and the remaining months.
For example, a Jia-year chart starts Bing-Yin, then Ding-Mao, Wu-Chen and so on. The exact birth interval determines how many steps to advance.
- Advance stem and branch in lockstep.
- Wrap from Gui back to Jia.
The mnemonic cannot repair a wrong year or month boundary
If the Year Stem was switched at Lunar New Year or the Month Branch came from a lunar month number, a correct Five Tigers lookup still produces a wrong Month Pillar.
The formula is deterministic calculation, not a prediction. Interpretation requires the complete chart after every pillar is verified.
- Validate prerequisites before lookup.
- No symbolic outcome from the mnemonic itself.
Sources and editorial basis
- 《三命通會》 (Sanming Tonghui)《三命通會》年上起月法：甲己之年丙作首等五組歌訣，從寅月順推十二月干A historical compilation covering stems and branches, Ten Gods, Nayin, Shen Sha, and multiple classical pattern systems.
- Hong Kong Observatory: Heavenly Stems and Earthly Branches香港天文台天干地支資料提供十干與十二支固定次序，五虎遁是在該循環上的月干映射An official modern reference for the canonical stem and branch orders, the sexagenary cycle, and calendrical use.
- OpenFate Editorial Methodologytests/bazi/test-pillar-invariants.ts 逐組驗證甲己、乙庚、丙辛、丁壬、戊癸年干的寅月起干及後續月序OpenFate separates deterministic chart calculation, traditional interpretation, and modern editorial explanation.