Four Pillars of Destiny
Your birth moment, written in eight characters
Year, month, day and hour each become a pillar of one Heavenly Stem and one Earthly Branch. We calculate them in code — with your birthplace's true solar time and the exact Start of Spring — and AI only writes the words.
What we calculate
- True solar time from your birthplace's longitude and the equation of time.
- Year and month by the exact solar terms — the Start of Spring (立春), not 1 January.
- Ten Gods, hidden stems, Na Yin, the twelve life stages and branch interactions.
- Luck Pillars from the minute-precise distance to the nearest solar term.
Your birth details
How a BaZi chart is read
BaZi (八字, 'eight characters'), also called the Four Pillars of Destiny (四柱), writes the moment of birth as four pairs of characters: one pillar each for the year, month, day and hour. Each pillar has a Heavenly Stem (天干) above and an Earthly Branch (地支) below, and every stem and branch belongs to one of the five elements (wood, fire, earth, metal, water) and is yin or yang.
The stem of the day pillar is the Day Master (日主): it stands for you. Everything else in the chart is read in relation to it through the Ten Gods (十神), which name the relation of each other character to the Day Master, such as Wealth (財), Officer (官), Resource (印), Output (食傷) and Companion (比劫). The month branch sets the season, which decides whether the Day Master is strong or weak, and from that follows which elements are favourable (喜用神).
Time enters through the Luck Pillars (大運): ten-year periods that start from the month pillar and run forward or backward depending on the year stem and sex. Each calendar year adds a flow-year pillar (流年). Readers put a luck pillar and a flow year beside the chart to talk about a given stretch of life.
Two details decide whether a chart is right. The year and month change at the solar terms (節氣), so a birth in early February belongs to the previous year if it falls before 立春, and the hour pillar should use true solar time (真太陽時) at the birthplace rather than clock time. Our calculator applies both, to the minute, and shows the moment it used.
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BaZi: common questions
- What is BaZi?
- BaZi (八字) is the Chinese Four Pillars system: your birth year, month, day and hour each become a pair of characters, a Heavenly Stem and an Earthly Branch, eight characters in all. A reading looks at the five elements they carry, the balance between them and how they change over time through the Luck Pillars.
- What if I don't know my birth hour?
- You can still get a three-pillar chart: year, month and day are enough for the Day Master, the season and most of the Ten Gods. The hour pillar adds the late-life and children palace and can change the strength reading. The calculator marks the chart as hour-unknown and leaves that pillar out rather than guessing.
- What is true solar time, and does it matter?
- True solar time is the time shown by the sun at your birthplace, not the standard clock of your time zone. In China the clock follows Beijing, so a birth in Urumqi is about two hours off solar time; in summer time the gap grows by an hour. Because the hour pillar changes every two hours, this can move your hour pillar. The calculator converts from the birthplace's longitude and the equation of time.
- What is the Day Master (日主)?
- The Day Master is the Heavenly Stem of your day pillar, one of 甲 乙 丙 丁 戊 己 庚 辛 壬 癸. It represents you in the chart. Its element and yin/yang set your basic nature, and every other character is classified by how it relates to it.
- What do 'strong' and 'weak' Day Master mean?
- Whether the Day Master gets support from the month branch (the season), from the other stems and from the hidden stems of the branches. A strong Day Master usually favours elements that drain or control it; a weak one favours elements that feed it. The chart shows the support ratio and how it was counted, because schools differ on the borderline cases.
- When do the Luck Pillars start?
- At the age given by the distance from your birth to the nearest solar-term boundary, counted as three days to a year. Forward for men born in yang years and women born in yin years, backward otherwise. The chart lists ten pillars with their start dates; see the guide on Luck Pillars for the full method.