How to Use BaZi Calculator
The BaZi Calculator creates a basic Four Pillars chart from a Gregorian birth date, birth time, time zone, and longitude. Enter the date first, then add the local birth time if you know it. If the exact time is unknown, enable the time-unknown option so the chart can show the year, month, and day pillars while leaving the hour pillar open.
Use the time zone field for the legal time zone at the birthplace, such as UTC+8 for Beijing or UTC-5 for New York during standard time. Longitude is used when true solar time is enabled. True solar time shifts the clock by the difference between the birthplace longitude and the standard meridian of the selected time zone. This can matter when a birth is close to a two-hour boundary.
The result area shows the Year Pillar, Month Pillar, Day Pillar, and Hour Pillar. Each pillar includes its Heavenly Stem, Earthly Branch, pinyin, Five Element, Yin/Yang polarity, and zodiac animal. The BaZi Calculator also summarizes the Five Elements with weighted bars, lists Hidden Stems inside each Earthly Branch, and gives a basic Ten Gods mapping based on the Day Master.
Formula & Theory - BaZi Calculator
The BaZi Calculator follows the standard structure of Four Pillars calculation:
BaZi = Year Pillar + Month Pillar + Day Pillar + Hour Pillar
Pillar = Heavenly Stem + Earthly Branch
Five Element score = stem weight + branch weight + hidden-stem weights
True solar time offset minutes = (longitude - timeZone * 15) * 4| Symbol | Meaning |
|---|---|
| Heavenly Stem | One of Jia, Yi, Bing, Ding, Wu, Ji, Geng, Xin, Ren, Gui |
| Earthly Branch | One of Zi, Chou, Yin, Mao, Chen, Si, Wu, Wei, Shen, You, Xu, Hai |
| Day Master | The Heavenly Stem of the Day Pillar |
| Hidden Stems | Stems traditionally stored inside each Earthly Branch |
Year pillars are based around Li Chun rather than January 1. Month pillars use solar-term boundaries, so a birthday early in a Gregorian month may still belong to the previous BaZi month. Day pillars follow the repeating sixty-day cycle. Hour pillars use the twelve double-hours, with Zi hour covering the late-night boundary.
This implementation is designed for a fast browser calculator. It includes the traditional mapping tables and a solar-term approximation suitable for learning and general reference. If the birth date is close to Li Chun, another monthly solar term, midnight, or a two-hour boundary, a specialist almanac or exact astronomical ephemeris may produce a different result.
Assumptions and Limits
The BaZi Calculator is not a fortune-telling authority. It does not promise results about destiny, career, marriage, wealth, health, or personality. Day Master notes and Ten Gods labels are brief cultural explanations so users can understand how the chart is assembled. Treat the output as educational and exploratory.
Use Cases for BaZi Calculator
The BaZi Calculator is useful for people studying Chinese metaphysics, calendar systems, and traditional terminology:
- Four Pillars learning - See how a Gregorian birth time maps to stems and branches.
- Day Master lookup - Identify the Day Stem used as the reference point for basic interpretation.
- Five Elements study - Compare visible stems, branches, and Hidden Stems in one chart.
- Solar-term awareness - Notice when a chart may depend on precise time or location.
- Shareable summary - Copy a clean text result for notes, discussion, or further research.
Because all calculations run in the browser, the BaZi Calculator is suitable for quick private exploration. For serious historical research or professional chart work, confirm boundary cases with precise birth records and high-accuracy solar-term data.