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Daily chart coordinate · 日柱

The day pillar anchors the chart

The day pillar is one pair in a continuously advancing sixty-day sequence. Its stem is the 日主 Day Master—the fixed comparison point used to name every other visible and hidden stem in the chart.

Four inscribed chart tablets in a Chinese observatory pavilion at the turn from night to dawn
日柱The cinnabar day tablet is central because its stem supplies the chart's relationship coordinate, not because it replaces the other three pillars.

Stem above · branch below

What the daily pair contributes

The day branch completes the daily stem–branch pair. The day stem also receives a second job: it becomes the reference for the Ten Gods relationship names.

  1. 01Visible stemThe Day Master · 日主

    Its phase and polarity are compared with every other concrete stem.

  2. 02Visible branchDaily branch position

    It is the branch paired with the stem at that point in the sixty-day cycle.

  3. 03Time scaleOne sexagenary day

    The pair advances daily and returns after sixty positions.

  4. 04Chart roleRelationship origin

    It names relations; it is not a score, element total or personality type.

Where this coordinate changes

The late Rat hour exposes two day boundaries

Most birth times give the same day pillar under both common conventions. The disagreement is confined to 23:00–23:59, before civil midnight but inside the Rat period.

  1. 01 · 00:00 convention

    Civil midnight opens the new day

    The current civil date keeps its day pair until 23:59, then advances at midnight.

  2. 02 · 23:00 convention

    Late Rat hour opens the next sexagenary day

    Under 晚子時, the first hour of Rat already belongs to the following day pair.

  3. 03 · Published result

    Keep the convention beside the pair

    When the two readings diverge, the site reports both instead of hiding a methodological choice.

The rule, not a personality shortcut

How the daily pair and Day Master are read

A verified calendar anchor and the elapsed-day count locate the date modulo sixty. The resulting first character becomes the Day Master; the second is that day's branch.

Calendar anchor + elapsed days mod 60 → day stem + day branch

  1. 01

    Locate the sixty-day position

    The count advances without restarting at a Gregorian month, lunar month or New Year.

  2. 02

    Apply the chosen day boundary

    Civil midnight and late Rat hour differ only during the 23:xx interval.

  3. 03

    Name relations from the stem

    Compare target phase first and polarity second to obtain one of the ten structural names.

Keep the coordinate precise

Common day pillar confusions

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

01
Is the Day Master a fifth pillar?
No. It is the Heavenly Stem already visible in the day pillar, given the special role of relationship reference.
02
Does a Day Master alone determine a person?
No. It is one fixed chart coordinate. The other pillars, branches, hidden stems and declared interpretive method remain separate evidence.
03
Why can charts disagree for a 23:30 birth?
One school advances the sexagenary day at 23:00; another waits for civil midnight. The hour stem also changes with the selected day stem.