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Four-Pillar Charting Method

bazi · method · BaZi · Four-Pillar Charting Method

Purpose

Map a birth event (date, time, and optional place) to four stem–branch pairs—year, month, day, hour—the sole skeleton for later Ten Gods, luck cycles, and annual pillars.

Inputs

InputRequired?Notes
Gregorian Y/M/DYesStarting point for calendar conversion
Clock hour/minuteStrongly recommendedWithout hour, hour pillar is unknown; day pillar may also be ambiguous at Zi boundaries
Birth longitude/latitudeOptionalOnly when enabling true solar time or checking time zone
SexFor luck cyclesNot needed for four pillars themselves; needed to start luck cycles

Read first: Calendars and Chart Time, Stems and Branches.

Step 1: Correct to true solar time?

  1. Take birth longitude and compare with the standard meridian of the civil time zone.
  2. Convert longitude difference to a time offset; apply fine correction from that day’s equation of time if the school uses it.
  3. Obtain “local apparent solar time for charting.”

If not enabled, use civil clock time (state the time zone). Details: True Solar Time. Chart records must mark whether correction was applied, or later verification is impossible.

Step 2: Fix the day pillar

  1. Map the charting date onto the stem–branch day sequence. Common practice uses a validated day-pillar table or day-count algorithm (sixty Jiazi cycle).
  2. Zi-hour day change must choose a rule first:
    • Enter the next day’s day pillar from 23:00; or
    • Change at 00:00.
  3. Near-boundary births should record both possibilities; do not silently adopt a default. See Zi Hour Day Change.

The day-pillar Heavenly Stem is the Day Master.

Step 3: Fix the hour pillar

  1. Assign the charting clock time to one of the twelve double-hours (Zi, Chou, Yin… Hai) to get the hour branch.
  2. The hour stem follows from day stem and hour branch via traditional “Five Rats escape” mnemonics (day stem fixes the Zi-hour stem, then proceed).
  3. If the moment falls on a pillar boundary, record the boundary convention used.

Step 4: Fix the month pillar

  1. Month pillars do not change on lunar new moons; they change at solar-term jie (not zhongqi): Lichun, Jingzhe, Qingming…
  2. Find which two jie bracket the birth moment to get the month branch (Yin month from Lichun, Mao from Jingzhe, and so on).
  3. The month stem follows from year stem and month branch via “Five Tigers escape.”
  4. Birth within minutes of a term change is high-risk borderline: mark the solar-term data source (which ephemeris or almanac).

Step 5: Fix the year pillar

  1. Traditional BaZi year pillars usually take Lichun as the year boundary—not Jan 1 or Spring Festival.
  2. Born before Lichun: year pillar uses the previous year’s stem–branch; after Lichun, the current year’s.
  3. Year stems/branches themselves come from the sixty Jiazi year sequence.

Step 6: Validate and output

After four pillars, output at least:

  • Full four-pillar stems and branches
  • Day Master
  • Used: time zone / true solar time on or off / Zi-hour day-change rule / solar-term data source

Optional next calculations: hidden stems, Na Yin, Ten Gods, emptiness, etc. (see Chart Fields).

Common errors

  • Changing year at Spring Festival or New Year’s Day.
  • Changing month at lunar month start.
  • Time zone mismatched to birth place without disclosure.
  • Omitting rules at Zi-hour or term-change boundaries.

Next steps

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