Free BaZi Calculator — Four Pillars of Destiny

The year pillar follows the sixty-year cycle of stems and branches, but the BaZi year begins at Lichun, the solar term that opens spring, not on 1 January or at Chinese New Year. A child born on 3 February belongs to the previous year's pillar. The month pillar is fixed by the Sun's longitude — each of the twelve jie terms opens a month — and the month stem follows the year stem by the classical "five tigers" rule. The day pillar is a continuous sixty-day count that has run unbroken for more than two thousand years. The hour pillar divides the day into twelve double hours starting at 23:00 and takes its stem from the day stem by the "five rats" rule.

All of this is computed from the Sun's position, so leap years, time zones and daylight saving cannot push a birth into the wrong pillar.

Double hours were defined by the Sun, not by a national time zone. Someone born at 12:50 clock time in western China is still in the 午 (11:00–13:00) hour by the clock, but the Sun there is more than an hour behind Beijing time, so the true solar time is around 11:40 and the hour pillar is the same only by luck. The calculator adds the longitude correction (four minutes per degree from the zone meridian) and the equation of time, reports the corrected solar time, and flags the hour pillar as tentative when the solar time lands within ten minutes of a double-hour boundary. If the correction pushes the birth across midnight, the day pillar moves with it.

The stem of the day pillar is the Day Master (日主) — you, in the chart. The other seven characters are read in relation to it. The calculator judges its strength in the classical order: first the month command (月令), the season it was born in, which carries about two fifths of the weight; then its roots, stems of its own element hidden in the branches; then the support or drain of the other stems, which weigh less than roots. Strength is the share of supporting against draining forces, and a chart is only called extreme when it might follow its dominant force or be dominated by its own — and then it says the useful element is uncertain rather than forcing one.

The useful element (用神) is chosen by what makes the chart strong or weak, as the Di Tian Sui teaches: a Day Master strong from its Seal is balanced by Wealth, one strong from its companions by the Officer (or by its Output when no Officer stands in the chart); one weakened by Wealth wants companions, one weakened by the Officer or by Output wants the Seal. In a summer birth without Water, or a winter birth without Fire, the climate comes first — the Qiong Tong Bao Jian rule. The card names the useful element; the AI reading also gets the full favourable and unfavourable sets. It decides which years, colours, directions and industries help you.

Every stem stands in one of ten relationships to the Day Master, the ten gods (十神): Companion and Rob Wealth (same element), Eating God and Hurting Officer (what the Day Master produces), Direct and Indirect Wealth (what it controls), Direct Officer and Seven Killings (what controls it), Direct and Indirect Seal (what produces it). The calculator labels the stem of every pillar and the main hidden stem of every branch with its ten god. Read together they describe career (Officer stars), money (Wealth stars), creativity and children (Output stars), learning and support (Seal stars) and peers (Companion stars) — and the spouse star, Direct Wealth for a man and Direct Officer for a woman.

BaZi is a timing system as much as a personality system. The luck pillars (大運) are ten-year periods that run forward or backward from the month pillar depending on the year stem's polarity and your gender — which is why the calculator asks for it. The starting age is the distance in days to the nearest jie term divided by three. Each luck pillar is shown with its stem's ten god so you can see which decade carries your useful element. The annual pillar (流年) for the current solar year is checked against your natal branches for clashes — a clash with the day branch is the classic marriage or relationship signal, one with the year branch the "year of change" — and for the Tai Sui year when the annual branch equals your natal year branch.

The card weighs Wood, Fire, Earth, Metal and Water across the stems and the hidden stems of every branch, with the month branch counting most, names the dominant element, and calls an element missing only when it appears in no stem and no hidden stem — an element stored in a branch is present even when you cannot see it. The AI BaZi reading also receives every interaction between the pillars — stem combinations and whether they bind or transform, clashes, six, half and triple combinations, directional combinations, harms and punishments — the interactions that turn a static chart into a story of alliances and tensions between the year (ancestors and society), month (parents and career), day (spouse) and hour (children), and puts a dedicated BaZi specialist on your chart to read them.