Bazi Four Pillars Calculator
Bazi turns the year, month, day and hour of birth into a heavenly stem and an earthly branch each, making four pillars of eight characters. The stem of the day pillar is the Day Master and stands for the person themselves; the relationships the other seven characters have with the Day Master are named the Ten Gods. The first step in reading a chart is not to look up whether a given God is favourable, but to judge whether the Day Master is strong or weak within the whole configuration — the same God can read in opposite ways in a strong chart and a weak one.
Cast a ChartWhere the four pillars come from
The year pillar changes at Lichun (立春, Beginning of Spring), not on the first day of the lunar first month — this is the point where Bazi and the folk calendar are most often confused. The month pillar changes at the twelve jie (節) among the twenty-four solar terms, with the moment of transition fixed to the minute. The day pillar follows the continuous sexagenary day count. The hour pillar is determined by the day stem together with the hour of birth. Schools differ over whether the early zi hour (早子時) belongs to the current day or to the next, so a chart born across midnight should state explicitly which convention it uses.
The Ten Gods and the hidden stems
Everything is measured from the Day Master: what is the same as it gives Shoulder-to-Shoulder (比肩) and Wealth Robber (劫財); what it produces gives Output Star (食神) and Hurt Officer (傷官); what it controls gives Regular Wealth (正財) and Side Wealth (偏財); what controls it gives Regular Officer (正官) and Seven Killings (七殺); what produces it gives Regular Seal (正印) and Side Seal (偏印). Besides its main qi, an earthly branch also holds residual qi and storehouse qi — the hidden stems — so a single branch often carries two or three layers of Ten Gods information at once. Counting only the Gods visible on the stems and ignoring the hidden ones is the most common beginner's omission.
Strength, weakness and the yong shen
Judging the strength of the Day Master involves three things: being in season (得令 — whether the month command supports it), having ground (得地 — whether the branch beneath it and the other branches give it a root), and having numbers (得勢 — whether characters of its own type are many). They need not all hold at once, so the judgement involves weighing them. The yong shen (用神) is the one link in the whole configuration that most needs to be supplied, or most needs to be held in check. ⚠️ Choosing a yong shen is itself a matter of schools — support-and-restraint (扶抑), climate adjustment (調候), bridging (通關), disease-and-cure (病藥) and others — and the same chart can yield different yong shen in different schools. That is not a question of anyone being wrong; each weights the judgement differently.
Luck pillars and annual pillars
The luck pillars (大運) run forwards or backwards from the month pillar, one step per decade, with the starting age converted from the number of days between the birth date and the adjoining solar term. The annual pillar (流年) is simply that year's stem and branch. The luck pillar sets the overall environment of a period and the annual pillar is one particular year inside it; the traditional order of reading is to look first at how the luck pillar relates to the natal chart, and only then to bring the year in, rather than reading a year on its own, detached from the luck pillar.
FAQ
Beginning of Spring and Lunar New Year fall on different days — which one does Bazi use?
Beginning of Spring. The year pillar changes at the exact moment that solar term begins, and has nothing to do with the first day of the lunar first month. Someone born between lunar New Year's Day and Beginning of Spring still belongs to the previous year pillar; someone born after Beginning of Spring but before lunar New Year's Day already belongs to the new one. For births near the turn of the year this makes a great deal of difference.
How is the strength of the Day Master judged?
Mainly by three things: whether the month command produces and supports the Day Master, whether the Day Master has a root among the earthly branches, and how many characters of the same element there are and where they sit. The three seldom all point the same way, so the judgement always carries an element of weighing. That is also why different readers can disagree about the strength of the same chart — and, following from that, choose different yong shen.
If an element is missing, does it have to be supplied?
The tradition does not hold that whatever is missing must simply be added back. Bazi looks at the balance and flow of the whole: sometimes the missing element is precisely the one not needed, and supplying it only makes matters worse; conversely an element that is present but excessive may be where the trouble actually lies. Choosing a name or arranging a space with “all five elements present” as the goal is a common misuse of the method.
How should a chart be cast for a birth in the early zi hour?
For the stretch from 23:00 to midnight, some schools count it as the zi hour of the day that is ending, others as belonging to the next day. The two methods produce different day pillars, which in turn changes the Day Master and the chart as a whole. This is a divergence with no settled answer, so in practice you state which convention you are using and read on that basis.
Can Bazi work out exactly what will happen?
Traditional Bazi describes tendencies, structure and the rise and fall of timing, not the prediction of specific events. It sits best as one point of reference for understanding your own temperament and the rhythm of your circumstances; concrete decisions involving health, finances or legal matters should be taken to the appropriate professionals.
Related terms
- Jia (甲) — Yang WoodFirst of the ten Heavenly Stems; yang wood, classically symbolized by the great tree that grows upward and provides shelter.
- Zi (子) — Rat Branch / Yin WaterFirst of the twelve Earthly Branches; yin water; the rat sign; rules midnight (23:00–01:00) and the heart of winter.
- Zhengguan (正官) — Regular OfficerElement conquering the Day Master, opposite polarity; represents lawful authority, official career, and the lawful husband (in female charts).
- Zhengyin (正印) — Regular SealElement producing the Day Master, opposite polarity; represents formal education, mother, lawful inheritance, and respected mentors.
- Shishen (食神) — Output StarElement produced by the Day Master, same polarity; represents creativity, flow, eating-and-drinking pleasures, and stable productivity.
- Lichun (立春) — Beginning of SpringThe first solar term, around February 3-5; marks the astronomical start of spring and the new year for traditional Chinese metaphysics.