Versioned calendar and astronomy libraries compute the chart. A language model does not invent pillars.
Rule-based chart · no AI pillar calculation
Free BaZi Calculator: Four Pillars, Day Master and Da Yun
Enter birth date, time, and place to calculate the Four Pillars, Day Master, timing metadata, and precision notes before any symbolic interpretation is added.
What does this BaZi calculator show?
The tool returns the Year, Month, Day, and Hour Pillars, the Day Master, precision notes, current luck-cycle metadata when the required direction inputs are available, and the rule version used for the calculation. It is designed for education and self-reflection, not medical, legal, financial, or guaranteed predictive advice.
Inspect the active conventions, libraries, boundary tests, and reference cases →
Li Chun, exact Jie boundaries, the 23:00 Zi-hour policy, civil time, apparent solar time, and Da Yun conventions are documented.
If a time correction crosses a branch, day, or solar-term boundary, the result reports reduced precision instead of hiding the conflict.
How does a BaZi calculator use birth date, birth time, and location?
Birth date anchors the day and year calculation. Birth time determines the Hour Pillar and may affect day-boundary handling. Birthplace is used to normalize historical timezone and check whether longitude-based apparent solar time could change a branch, day, or solar-term boundary.
Why true solar time can change a BaZi chart
Clock time is a civil convention. Apparent solar time adjusts the moment using location and solar position. Most charts do not visibly change, but a birth close to a two-hour branch, day boundary, or solar term needs a precision warning rather than one silent answer.
What are Day Master, Ten Gods, Five Elements, and Luck Pillars?
The Day Master is the Day Stem used as the chart reference point. Ten Gods describe how other stems relate to it. Five Elements show the chart's symbolic distribution. Luck Pillars add ten-year timing context after the natal structure is calculated.
Why different BaZi calculators may disagree
Differences usually come from historical timezone data, daylight-saving handling, Li Chun versus Lunar New Year, exact solar-term boundaries, Zi-hour day rules, solar-time policy, and how Da Yun starting age is converted or displayed.