四 Free BaZi Four Pillars Calculator

The year does not begin on 1 January, and not at Chinese New Year either. In BaZi the year turns at Li Chun, the moment the Sun reaches 315° of longitude, usually 3–5 February. Umbriel computes that moment from the Sun's true position, the same engine that casts its Western charts, so a birth on the evening of 4 February lands in the right year. The Chinese Zodiac page dates the animal from Chinese New Year on purpose; the two pages say which rule they use.

The month pillar is the loudest character in the chart. Its branch comes from the Sun's longitude in 30° steps from Li Chun (the twelve jie), and its stem follows the Five Tigers rule from the year stem. The month is the season your Day Master was born into: whether the element around you feeds yours, drains it, or presses on it.

The day pillar is a count: the sixty-day cycle of stems and branches, which every classical source anchors the same way (1 January 1900 was a 甲戌 day; 1 January 2000 a 戊午 day). The hour pillar uses the twelve double-hours by solar time, so Umbriel corrects your clock time by your birthplace's longitude before reading it, and the Five Rats rule gives its stem from the day's.

Each stem against the Day Master is one of the Ten Gods: Friend, Rob Wealth, Eating God, Hurting Officer, Indirect and Direct Wealth, Seven Killings, Direct Officer, Indirect and Direct Resource. They are the relationships in the chart: what supports you, what you produce, what you work for, what governs you. Umbriel names each one in plain words, with the traditional name beside it.

The luck pillars are ten-year seasons. The classical rule runs them forward or backward from the month pillar depending on the year's polarity and the person's sex, and the first begins at an age set by the days to the nearest solar term, three days to a year. You choose the direction with one tap and see eight pillars, each with its element pair and its Ten God against your Day Master.

Every pillar turns on a boundary, and each boundary is the one a careless implementation gets wrong. THE YEAR TURNS AT LI CHUN, the Sun reaching 315°, not at Chinese New Year: a birth in the first days of February can belong to one animal in BaZi and the next one on the Chinese zodiac page, which is not a contradiction but two different calendars, and Umbriel computes both and names which is which. The year stem is (year − 4) mod 10 and the branch (year − 4) mod 12, with 1984 as 甲子. The MONTH branch is read straight off the Sun's true longitude — 寅 from 315°, then one branch every 30°, the twelve 節 — so the month changes at the solar term and never on the first of anything; its stem follows the Five Tigers rule from the year stem. The DAY is the sexagenary count (JDN + 49) mod 60, checked against three anchors that every source agrees on: 1 January 1900 = 甲戌, 1 October 1949 = 甲子, 1 January 2000 = 戊午. It turns at local midnight, and the "late 子" school that turns it at 23:00 is NAMED on the page rather than quietly applied, because the two schools disagree about roughly one birth in twenty-four. The HOUR is a double-hour in LOCAL SOLAR time — the birth clock corrected by four minutes for every degree the birthplace lies from its zone's meridian, which moves the pillar for anyone born near the edge of a wide zone — with its stem by the Five Rats rule from the day stem. The Ten Gods come from each stem against the Day Master by element cycle and polarity, and the hidden stems are the classical 藏干 of each branch, main, middle and residual. Luck pillars run forward for a yang-year man or a yin-year woman and backward otherwise, the first beginning at the distance from birth to the neighbouring solar term divided by three, three days to a year, then ten years each. The Sun's longitude comes from the app's own VSOP87 engine when it is loaded and from a compact Meeus series (±0.01°) otherwise, and the result reports which was used, because a quarter of an hour at a term boundary is the difference between two month pillars.