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Seasonal chart coordinate · 月柱

The month pillar follows solar terms

The month pillar is not a Gregorian month and not the numbered lunar month. Its branch changes at one of twelve 節 jié solar terms, while its stem is derived from the year stem and advanced with the branch.

Four inscribed chart tablets in a Chinese observatory pavilion at the turn from night to dawn
月柱The month tablet follows the seasonal gates between Li Chun and the next year's Minor Cold term.

Stem above · branch below

What the seasonal pair contributes

A solar-term month provides a branch position in the Tiger-to-Ox sequence and a derived Heavenly Stem. Together they locate the birth within the seasonal year.

  1. 01Visible stemDerived month stem

    The Five Tigers rule starts from the year stem, then advances monthly.

  2. 02Visible branchTiger through Ox

    Each of the twelve jié terms opens the next fixed branch month.

  3. 03Time scaleOne solar-term interval

    The boundary is an astronomical timestamp, not a whole civil date.

  4. 04Chart roleSeasonal visible pillar

    Its two characters sit between the annual and daily coordinates.

Where this coordinate changes

Twelve jié terms open the twelve branch months

The twenty-four solar terms alternate between jié boundaries and zhōngqì midpoints. Only the twelve jié terms change the month pillar in the method used here.

  1. 01 · Opening

    Li Chun begins Tiger

    立春 opens the 寅 Tiger month and establishes the first branch of the seasonal sequence.

  2. 02 · Advance

    Each later jié moves one branch

    Awakening of Insects opens Rabbit, Clear and Bright opens Dragon, and the sequence continues through Ox.

  3. 03 · Exact edge

    Time decides a boundary-day birth

    A birth earlier and later on the same civil date can fall in different month pillars when a term occurs that day.

The rule, not a personality shortcut

The Five Tigers rule supplies the month stem

The year stem chooses the stem paired with the opening Tiger month. From there both stem and branch advance one position at each new jié term.

Year stem group → Tiger-month stem → advance once per jié boundary

  1. 甲 / 己 years

    丙寅 · Bing Tiger

    Jia and Ji years open their Tiger month with the Bing Fire stem.

  2. 乙 / 庚 years

    戊寅 · Wu Tiger

    Yi and Geng years open with the Wu Earth stem.

  3. 丙 / 辛 years

    庚寅 · Geng Tiger

    Bing and Xin years open with the Geng Metal stem.

  4. 丁 / 壬 years

    壬寅 · Ren Tiger

    Ding and Ren years open with the Ren Water stem.

  5. 戊 / 癸 years

    甲寅 · Jia Tiger

    Wu and Gui years open with the Jia Wood stem.

Keep the coordinate precise

Common month pillar confusions

These distinctions prevent one useful label from being stretched into a claim the chart does not make.

01
Is the month pillar my lunar birth month?
No. This chart convention uses the twelve jié solar-term intervals. Lunar months belong to a different calendar count.
02
Does the month change on the first day of a Gregorian month?
No. The change occurs at the exact solar-term moment, usually several days into the civil month.
03
Why can the same branch month have different stems?
The branch sequence is fixed, but the opening Tiger stem depends on the year stem. Five valid stem cycles therefore pass through each month branch.