Most Bazi sites ask a language model to "calculate" the chart. Models are unreliable at stems and branches — and the hour pillar is where they fail most. We split the work: the program calculates, the model writes.
Pillars, hidden stems, Ten Gods, Na Yin, Luck Pillars and annual pillars are all computed by lunar-javascript, verified field by field against the classical Python implementation it derives from. During development we ran ten boundary cases — leap day, early and late zi hour, month-pillar changes across Jingzhe and Qingming, the year boundary — covering 110 fields with zero differences.
The late zi hour (23:00–24:00) follows the convention of not advancing the day pillar, matching that reference implementation. Other schools handle this differently; if you follow one, cross-check elsewhere.
Hours are defined by the sun's actual position at your birthplace, not by the clock. Two corrections apply:
Daylight saving is resolved through the IANA time zone database, including China's 1986–1991 DST — those years ran at UTC+9, not UTC+8. Many calculators miss this entirely.
Your result page states the exact correction in minutes so you can verify it against any other tool.
Element strength is a weighted score: month branch heaviest, day branch next; hidden stems graded main, middle, residual. Day Master strength compares support (same element plus producing element) against drain and control.
To be clear: this part is a heuristic in common modern use, not a quotation from the classics. Schools disagree on how to judge strength and useful elements. Our approach is to name the method on the page — for example "support-and-restrain" — so you can judge the reasoning rather than accept a conclusion.
Quotations from the San Ming Tong Hui are taken from the Siku Quanshu edition (twelve volumes, 790 sections, transcribed on Wikisource). We cite volume and section, and paraphrase rather than translate wholesale.
If a quotation ever looks invented, tell us — fabricated citations are the one unforgivable error in this kind of tool.
Bazi is an interpretive framework, not a predictive science. It describes tendencies and structure; it cannot tell you what will happen next Tuesday.
We do not promise outcomes, do not give medical, legal, or financial advice, and do not serve minors. The disclaimer at the end of every reading is not boilerplate — it is the actual scope of the method.
Birth date, time and city are stored in our own database to generate your reading and keep shareable links working. IP addresses are recorded only as hashes, for rate limiting. We do not train models on your data.
To delete a record, write to hello@bazi.casa with the chart ID.
Free, with true solar time correction and the full chart.