BaZi Four Pillars Calculator
Your Chinese Astrology Chart
BaZi (八字, "Eight Characters"), also called the Four Pillars of Destiny (四柱), is a classical Chinese system that maps a person's chart from their birth date and time. Each of the four pillars (Year, Month, Day and Hour) combines one of the 10 Heavenly Stems with one of the 12 Earthly Branches. The stem of the Day pillar is your Day Master, the anchor for reading the balance of the five elements.
Traditional Chinese metaphysics, presented for cultural interest and self-reflection, not a prediction system. 18+.
Yi Wei 乙未
- •cutting off what is bad
- •surgery if needed
- •starting anything new
Build your full BaZi chart from your birth date
You get all four pillars (Year, Month, Day, Hour) at once: the Heavenly Stem and Earthly Branch of each, your Day Master (日主, the core self), the 5-element balance, and per-pillar reading. Add your birth hour if you know it; without it the chart is still accurate with three pillars.
This data is stored only in your browser, never sent to a server.
Everyone has four pillars: Year, Month, Day, Hour. Each pillar is one Heavenly Stem (天干, 10 celestial stems) plus one Earthly Branch (地支, 12 terrestrial branches). Four pillars × two characters = eight characters, which is why it is called BaZi (八字 = eight characters). The stem of the Day pillar is your Day Master (日主), the reference point for reading every other element.
The BaZi year does not follow the Gregorian or Lunar New Year calendar. It begins when the Sun reaches 315° of celestial longitude (Lichun 立春, around 4 February). Born on 4 Feb but before the exact Lichun moment? Your Year pillar still belongs to the previous zodiac year. We compute the Lichun instant astronomically each year, so the ±1-day shift is handled correctly.
The Month pillar is set by the 12 jié (節): points 30° apart along the Sun's longitude: Lichun→Yin, Jingzhe→Mao, Qingming→Chen, and so on. The branch is derived from the astronomical term instant, and its stem follows the Wu Hu Dun (五虎遁, Five Tigers) rule from the year stem.
The Day pillar uses the Julian Day Number, anchored at 1 Jan 2000 = Wu Wu (戊午). The Hour pillar: the branch comes from the 12 two-hour shichen (Zi = 23:00-01:00), and its stem follows the Wu Shu Dun (五鼠遁, Five Rats) rule from the day stem. The late-Zi (晚子时) rule applies: born after 23:00 → the day pillar has already rolled over.
BaZi (the Four Pillars of Destiny) is a classical Chinese metaphysical system for mapping a person's temperament and energy cycles, used for generations as a tool for self-reflection, not a fixed prediction. Solar longitude is computed with astronomical algorithms (Meeus, Astronomical Algorithms, ch. 25); the Day pillar uses the Julian Day Number method; month and hour stems follow the classical Wu Hu Dun & Wu Shu Dun rules. For cultural interest and entertainment; life decisions remain yours. 18+.