How we compute your chart

The pipeline, step by step

1 · Clock time → true solar time

The classical system predates time zones: “midnight” and “noon” mean the sun’s position, not your government’s. We resolve your birthplace to coordinates and a historical IANA timezone, reconstruct the UTC offset that actually applied on your birth date (including DST and historical zone changes), then correct for your longitude to reach true solar time. For births far from a zone’s central meridian the correction runs tens of minutes — enough to flip an hour pillar, and near midnight, the entire day pillar. When you skip the city, we say the chart uses assumed clock time rather than silently pretending precision we don’t have.

2 · Month pillars from solar terms — never calendar months

BaZi months are astronomical: each begins at a solar term (节气), the moment the sun crosses a 15° ecliptic boundary — not on the 1st, and not at the lunar new year. A birth on the cusp day belongs to one month before the term’s exact hour and the next month after it. The engine carries the term table and resolves cusps to the hour, which is where a large share of wrong charts on free calculators come from.

3 · The sixty-cycle and the midnight boundary

Day pillars advance through the sexagenary cycle continuously — there is nothing to “look up,” only exact day-boundary arithmetic in true solar time. Late-night births (the late 子 Zi hour) are the classic disagreement among schools; we compute them consistently and flag the ambiguity instead of hiding it.

4 · Hidden stems, element weights, and strength

Each earthly branch conceals one to three hidden stems (藏干) — the reason two charts with identical visible characters can behave differently. Element counts weigh visible and hidden stems; Day Master strength then scores what feeds you (Resource, Peer) against what spends you (Output, Wealth, Power). Strength is the hinge of interpretation — a strong and a weak chart read the same input in opposite directions, which is exactly what a full analysis walks through.

5 · Validation: 12/12 reference gates

The engine was designed and tuned by a practicing bazi master working from the classical corpus — the 《三命通会》 (San Ming Tong Hui) and 《滴天髓》 (Di Tian Sui) lineage — and is validated against a fixed battery of reference charts covering solar-time corrections, solar-term cusps, midnight boundaries, and hidden-stem weighting: 12 out of 12 gates pass before any version ships. When a classical source and a modern convenience disagree, the classical source wins.

What the engine does not compute

The decade layer. In BaZi, a life moves through ten-year pillars (大運), and reading them is a different calculation from reading the chart itself. Rather than pad the Operating Manual with a templated version of it, we leave it out entirely: the Manual reads the instrument, the annual forecast reads the year, and the decade layer ships as its own document when the calculation meets the same 12/12 bar as everything else. If a section isn’t computed to that standard, it isn’t sold.

What we refuse to claim

No chart predicts your future, and we will not pretend otherwise. PILLARS readings are a structured lens for self-reflection — descriptive patterns you can test against your own life, never deterministic claims about health, money, relationships, or fate, and never a substitute for medical, financial, legal, or psychological advice. If a claim on this site ever fails that standard, tell us and we will fix it.