Month Pillar in Bazi (月柱)
Learn how exact Jie boundaries determine the Month Branch, how the Year Stem derives the Month Stem, and why the Month Pillar is not a lunar month.
Overview
The Month Pillar is the stem-branch pair for the solar-term month containing the birth instant. Its branch changes at the twelve Jie boundaries, while its stem is derived from the resolved Year Stem through the Five Tigers sequence. The Month Branch also carries the month command, a central seasonal reference in Ziping analysis. It is not the numbered lunar month and cannot be read without the Day Master and whole chart.
At a glance
- Components
- Month Stem and Month Branch
- Branch boundary
- Twelve exact Jie transitions
- Stem rule
- Five Tigers from the Year Stem
- Seasonal role
- Carries the month command
- Classical image
- Seedling or developmental environment
- Not equivalent to
- A numbered lunar-calendar month
Determine the Month Branch from the current Jie interval
Compare the normalized birth instant with exact solar-term transitions in one time basis. The Tiger month begins at Li Chun, followed by one branch per Jie interval.
Do not switch at lunar month day one or use an approximate fixed date. Minute precision matters only when the supported birth-time range can cross the actual transition.
- Store the surrounding Jie instants.
- Test immediately before and after each boundary.
Derive the Month Stem from the resolved Year Stem
The Month Stem is not chosen from the month number alone. Five Tigers establishes the Tiger-month stem from the Year Stem, then advances through the twelve months.
A corrected Year Pillar can therefore change the Month Stem even when the Month Branch stays the same. Downstream Ten Gods must be recomputed from the corrected pair.
- Validate the Five Tigers invariant.
- Never patch the displayed month pair manually.
Distinguish Month Pillar from month command
The Month Pillar contains a stem and branch; the month command is the seasonal authority carried primarily by the Month Branch. They overlap but are not synonyms.
Pattern, strength, and climate methods use the seasonal evidence differently. A responsible page names the method instead of implying that one month label completes every assessment.
- Use the full pair for pillar relations.
- Use the branch and seasonal depth for month command.
Treat family and career analogies as bounded traditions
Some schools associate the Month Pillar with parents, upbringing, peers, or occupational environment. These are positional prompts and can conflict across schools.
Do not infer a parent’s character, employment history, or a guaranteed life stage from the Month Pillar. Cross-check Ten Gods, other pillars, timing, and real information.
- State the school-specific palace lens.
- Avoid factual claims about relatives.
Sources and editorial basis
- 《淵海子平》 (Yuanhai Ziping)「看命入式」以月為苗，並在子平法中把月令作為命局季節與格局的重要起點A foundational Ziping reference for branch months, hidden stems, roots, and stem-branch relationships.
- 《三命通會》 (Sanming Tonghui)卷二論月令與四時氣候，強調月提為主並須兼看全局干支A historical compilation covering stems and branches, Ten Gods, Nayin, Shen Sha, and multiple classical pattern systems.
- OpenFate Editorial Methodology月柱的節氣計算、五虎遁月干與月令解讀分層保存，避免以農曆月份直接代替月柱OpenFate separates deterministic chart calculation, traditional interpretation, and modern editorial explanation.