In a Bazi (八字) chart, the eight stem-branch characters are not equal — one of them is the coordinate origin the other seven are read against, and that one is the Day Master (日主, rizhu). What Is Bazi located it as the stem of the day pillar; this article goes one layer down: how the Day Master is fixed, and how the question every reader meets once the pillars are laid out — strong, or weak? — is actually answered. In three moves: fix the day stem, read its strength, then read the ten gods against that strength.
What the Day Master is#
The Day Master, also called the Day Element (日元, riyuan), is the stem of the day pillar — the upper of the two characters in the day column. It stands for the person themselves; the other seven characters are all read in relation to it.
Taking 甲子 丙寅 戊辰 壬戌 as the example: the day pillar is 戊辰, with 戊 above and 辰 below, and the upper stem is taken, so the Day Master is 戊 — yang earth. To say “this person is a wu-earth” is to point at this single character, and it has nothing to do with the year pillar. The Chinese zodiac animal is read from the year branch, the Day Master from the day stem — one looks at the year, the other at the day, and the two are routinely confused. Rizhu (主, “master”) and riyuan (元, “origin”) name the same thing under two readings: the one character that is “master” and “origin” of the chart.
How the Day Master is determined#
Fixing the Day Master takes three steps:
- Lay out the four pillars. The day pillar in particular must be looked up from a calendar (a wannianli 万年历); it cannot be done by mental arithmetic, and schools differ on whether the day turns over at the 23:00 hour or at true midnight. Hand calculation is error-prone, so the site’s Bazi Calculator is the practical way to lay out and check the pillars first.
- Take the stem of the day pillar — the upper of the two day characters, not the branch below it.
- Identify its wuxing (五行) element and yin-yang polarity. Each of the ten stems carries an element and a parity, and the two together give the full Day Master:
| Day Master | 甲 | 乙 | 丙 | 丁 | 戊 | 己 | 庚 | 辛 | 壬 | 癸 |
|---|---|---|---|---|---|---|---|---|---|---|
| Element | Wood | Wood | Fire | Fire | Earth | Earth | Metal | Metal | Water | Water |
| Polarity | Yang | Yin | Yang | Yin | Yang | Yin | Yang | Yin | Yang | Yin |
So there are ten possible Day Masters, and “wu-earth” (戊土) is more precise than “earth” — within the same element, 戊 is yang earth and 己 is yin earth, with different imagery and different favorable relations.
How strong is the Day Master#
Fixing the Day Master is only the start. Its strength is what divides one chart from the next, because it sets the direction for everything read afterwards. “Strong” or “weak” is not good-or-bad — it is whether the Day Master is helped and supported more than it is checked and drained by the rest of the chart. Tradition looks in three places:
| Criterion | What it examines | Sign of strength |
|---|---|---|
| In season (deling 得令) | whether the month branch shares the Day Master’s element or generates it | the month command is of the same element, or generates the Day Master |
| Has root (dedi 得地) | whether any branch hides a stem of the same element | a “passing root” (tonggen 通根) in the branches |
| Has support (deshi 得势) | whether the other stems help or generate the Day Master | many of the same element, or of the element that generates it |
Of the three, being in season weighs most. The month command (yueling 月令) is the climate of the chart; the qi in command decides whether the Day Master holds the season — so strength is always read from the month branch first. Wu-earth born in a Dragon, Dog, Ox, or Ram month is in season; born in a Tiger or Rabbit (wood) month it is checked, and starts one degree weak.
The three need not all hold. All three make it strong, none make it weak, one or two call for weighing — strength is a continuous lean, not an on-off switch. The middle ground is where most real charts sit, and it is also where Bazi is hardest and most argued.
What strength decides: the ten gods#
The point of judging strength is to fix the favorable and unfavorable (xiji 喜忌) — and this is the seam where the Day Master meets the ten gods:
- A strong Day Master has a surplus of itself, and favors being checked, drained, or consumed — that is, it favors wealth, officer/killing, and eating/hurting gods, and dislikes more resource or peer gods.
- A weak Day Master has too little of itself, and favors being generated and supported — that is, it favors resource and peer/rob gods, and dislikes further checking or draining.
So the same ten-god means opposite things in different charts: direct wealth is favorable for a strong Day Master but a burden to a weak one; seven killings can be put to use when the Day Master is strong, but attacks it when the Day Master is weak. The claim in What Is Bazi that “the ten gods are not good-or-bad labels” is rooted exactly here — to read a ten god’s fortune without the Day Master’s strength is meaningless. The one character in the chart best able to carry the favorable direction is the yongshen (用神, “useful god”); that is an advanced topic, and at the entry stage it is enough to master the correspondence between strength and favorable/unfavorable first.
Classical source#
The practice of taking the day stem — rather than the year stem earlier readers had used — as the self of the chart is the defining move of the Ziping (子平) school, codified in the Song-dynasty compilation Yuanhai Ziping (《渊海子平》), the foundational text all modern Bazi descends from. The strength-and-useful-god reading the Day Master anchors was carried further by two later classics: Sanming Tonghui (《三命通会》, “Comprehensive Meeting of the Three Fates”), the Ming-dynasty synthesis by Wan Minying (万民英) that works out the day stem as the person of the chart and treats the month command as the chart’s governing climate; and Ditian Sui (《滴天髓》, “Dripping Heaven Marrow”), the text most cited for reading Day Master strength and selecting the useful god, whose terse lines were turned into the working method used today by the Qing commentator Ren Tieqiao (任铁樵). The attribution of Ditian Sui itself to the Ming figure Liu Bowen (刘基) is a later tradition’s retelling rather than a documented fact; what can be pointed to is the received text with its commentaries.
Related: What Is Bazi · Bazi Calculator · back to Destiny · Foundations