How the Day Master is found, and what “strong” and “weak” mean

The Day Master (日主) is the heavenly stem of the day pillar. There is nothing to calculate once the chart is built: the sign is simply there, in the third column. What takes work is reading its strength, because the whole chart is weighed against it.

Finding it

The example throughout these materials is a woman born on 21 March 1990 at 10:30 in Madrid; the chart was calculated by the BaziArt engine with true solar time. Nothing about this chart is special; it was chosen because it illustrates several of the rules described here.

The stem of the day pillar is 乙, Wood yin: the Day Master of this chart. The engine's verdict is “strong”.

There are ten possible Day Masters: five elements, each in a yang and a yin form, and each with its own traditional image. The ten pages describe them one by one.

Strength: three questions

Traditional texts judge the Day Master by three criteria. The two-out-of-three decision rule, the coefficients and the thresholds below are the documented BaziArt method, not a universal classical formula; a second, weighted method runs alongside and is described at the end of this section.

1. The season: the month branch 卯 is the Day Master's own season, and the stem ruling the month on that day is 乙; coefficient 1.0 — met.
2. The roots: the Day Master's element is found among the hidden stems of the branches — met.
3. The support: of the three open stems of the year, month and hour, 0 support the Day Master and 3 do not (authority 2, wealth 1) — not met.

Two criteria out of three are met, so the Day Master counts as strong in this system.

The season is the branch of the month pillar. Every element has a season in which it is in command: Wood in spring, Fire in summer, Metal in autumn, Water in winter, Earth in the four transitional months. The engine also looks at which hidden stem rules the month on the day of birth; the coefficients (1.0, 0.8, 0.7, 0.4) are on the calculation method page.

The roots are the Day Master's own element among the stems hidden in the earthly branches of any pillar, or a combination of branches that produces that element. A Day Master with no roots is read as standing without ground even when the season is right.

The support is the open stems of the year, month and hour: how many belong to the Day Master's element or to the element that feeds it, against how many do not. The Day Master itself is not counted.

The second method. The engine also computes a weighted share of the Day Master's element and its resource among all signs, open and hidden. The three criteria decide the verdict; the share overrides them only at the extremes (above 55 percent the chart counts as strong, below 25 percent as weak), and when the two methods disagree the app says so under “why I see this”.

What the verdict means, and what it does not

“Strong” and “weak” are not good and bad. In this system a strong Day Master is one that holds more than it needs, so the reading looks at what draws on it: output, wealth, authority. A weak Day Master is one that holds less, so the reading looks at what feeds it: resource and companions. This is the app's first-pass balance for ordinary charts; special and follow structures are read by their own rules, which the library explains. The app shows the balance the chart is read to need, with “why I see this” under it.

The verdict can also change with the hour of birth. When the hour is unknown, the engine computes all twelve possible hour pillars and reports how many of them agree; the calculator shows that count instead of pretending to know.

In the app

The chart screen shows the Day Master, its verdict and the three criteria. Tapping the term opens the library entry in two registers. Nothing here is a statement about the person: it is how this system weighs eight signs against one.