What is BaZi and how does it work?

The machinery runs on a small set of fixed counts. If you remember these, the rest of the system falls into place:

• 10 Heavenly Stems 天干 — 甲乙丙丁戊己庚辛壬癸 — the five elements, each in a yin and a yang form.
• 12 Earthly Branches 地支 — 子丑寅卯辰巳午未申酉戌亥 — the same twelve that give the zodiac animals.
• 60 combinations. Stems and branches pair in a cycle of 60, so the same stem-branch pair returns only once every 60 years — and the day pillar runs on its own unbroken 60-day cycle.
• 24 solar terms 节气 divide the solar year and set the month pillar — not the calendar month.
• 12 double-hours 时辰 of two hours each divide the day and set the hour pillar.
• 10-year luck cycles 大运 step through life in ten-year chapters, forward or backward from the month pillar.

Counts as used in the classical system and as implemented in this site's chart engine; the engine's outputs were checked against the same birth data in the Chinese and English editions (five test charts, all fields matching, November 2026).

Each pillar answers to a different clock, and getting the clocks right is most of the work:

Pillar	Set by	The boundary most people get wrong
Year 年柱	The birth year	It turns at 立春 Lìchūn (Beginning of Spring, around 4 February) — not 1 January, and not Lunar New Year. A baby born on 3 February 2024 and one born on 5 February 2024 have different year pillars.
Month 月柱	The solar term 节气 season	Months turn at the solar terms, the astronomical markers of the solar year — never on the 1st of a month.
Day 日柱	The 60-day cycle	The day pillar is counted from an unbroken cycle of 60 days that has run for centuries; it does not reset with any year or month.
Hour 时柱	The double-hour 时辰 and the day stem	Each two-hour block has a branch; which stem sits on it depends on the day's stem, by a fixed table. The late-night 子时 (23:00–01:00) is a known school difference: some traditions roll the day over at 23:00, others at midnight — this site's engine follows the 23:00 rollover and says so on the chart page.

Before any of that, the birth moment is converted to Beijing time, the classical basis of the calculation, and — if you ask for it — corrected to true solar time 真太阳时 from the birthplace longitude, because clock time is a political convenience and the tradition reads the sun. That correction occasionally moves the hour pillar, and the chart says when it has been applied.

Setting the pillars is arithmetic. Reading them is where the system earns its keep, and it works in four moves:

1. Find the Day Master 日主. The stem of the day pillar stands for you. Everything else is read by its relationship to this one character.
2. Count the five elements. Each stem and branch carries an element, and each branch hides one to three more inside it (藏干, hidden stems). The count shows which elements the chart is rich in and which it lacks — the raw balance of the pattern.
3. Name the ten gods 十神. The other seven characters are sorted by how they relate to the Day Master: the element that produces you, the one you produce, the one that controls you, the one you control, and your own element as a peer — each split by yin and yang. Wealth, authority, expression, support and companionship all enter the reading through these ten named relationships. They are called “gods” by tradition; they are really roles.
4. Mark the favourable elements 喜用神 and the classical stars 神煞. Weighing the Day Master's strength against the rest of the chart gives the elements that balance this particular pattern — the favourable ones. The stars are traditional markers attached to particular stem-branch combinations, read as colour rather than verdict.

On WenYiJu every paragraph of a report carries a basis line naming the rule it came from, so you can see which step produced which sentence.

A chart is fixed; life is not. The system handles that with the luck cycles 大运: ten-year chapters that step forward or backward from the month pillar, the direction depending on the year stem's yin or yang and on gender. Each decade brings a new stem-branch pair into play, and the reading asks how that pair interacts with the fixed chart — supporting the Day Master, challenging it, or bringing out a god that was quiet before.

Think of it as weather against landscape: the chart is the terrain, the luck cycle is the season passing over it. The same decade can read very differently on two charts, because the terrain is different. That is why BaZi readings always name the starting age of the first cycle — it is part of the calculation, not decoration.

Take the sample chart used throughout this site — a man born 15 June 1990, 10:30. The engine casts it as:

Pillar	Stem–Branch
Year	庚午 Gēng Wǔ
Month	壬午 Rén Wǔ
Day	辛亥 Xīn Hài
Hour	癸巳 Guǐ Sì

The Day Master is 辛 Xīn Metal — in the tradition's own image, “the finished jewel, not the ore: refined, exacting, quietly proud”. The chart is read as weak Day Master, with Earth as the favourable element, and the first luck cycle runs ages 8–17, 癸未 Guǐ Wèi, from 1997. Notice what the example shows: the same birth data, run through the same rules, gives the same four pillars every time. The interpretation is an art; the chart itself is arithmetic — and you can check this one yourself on the chart caster.

BaZi describes a pattern and the seasons that move through it. It does not announce events, name dates, or settle decisions — and this site never presents it that way. Read it as classical Chinese culture: a traditional language for tendencies and timing, useful for reflection, not a basis for medical, legal or financial decisions. Know the pattern, not the fate — and keep the steering wheel in your own hands.

Cast your own chart — free.

Enter a birth date, hour and gender on the home page and the full chart with its Character chapter is computed on the spot. No sign-up.

Cast my BaZi chart

Want the full overview first? Read BaZi — the Four Pillars, explained, find your zodiac sign, or check today's almanac.