Your birth year determines a grand movement (大运, Dayun) — one of the five climatic movements (Wood, Fire, Earth, Metal, Water) that governed the atmosphere during the year you were born. TianJi uses this single data point to produce a low-friction wellness snapshot: you enter your birth year, and the tool resolves the governing movement, its sufficient-or-deficient state, and the Sitian-Zaiquan qi pair that shaped the year's two halves.
How the birth-year grand movement is calculated
The calculation is straightforward and entirely deterministic. The heavenly stem of your birth year in the sexagenary cycle maps to one of the five movements: stems Jia and Ji map to Earth, Yi and Geng to Metal, Bing and Xin to Water, Ding and Ren to Wood, and Wu and Gui to Fire. Whether the stem is yang (odd) or yin (even) determines whether the movement is in a sufficient (太过) or deficient (不及) state. 《素问·天元纪大论》 and 《素问·六元正纪大论》 catalogue the climatic character of all sixty possible year configurations, and TianJi draws directly from this catalogue.
What the snapshot can and cannot tell you
What the snapshot tells you is the climatic backdrop of your birth year — not your personality, not your destiny, and not your health status. A person born in a Wood-sufficient year entered the world during a period of strong wind and vegetative growth; someone born in a Water-deficient year arrived during a relatively mild winter. Classical wellness theory suggests that these climatic conditions may colour one's baseline tendencies — for example, a tendency toward restlessness in a Fire year or toward dryness-related sensitivity in a Metal year — but these are general correspondences, not clinical findings.
The full climate picture TianJi resolves
TianJi computes the full picture: the grand movement, the Sitian (司天) qi that governed the upper half of your birth year, the Zaiquan (在泉) qi that governed the lower half, and the overall "year tone" (年气) that synthesises these into a single seasonal character. Each element of the snapshot carries a citation to the relevant Suwen passage, so you can trace exactly where the pattern comes from.
An educational on-ramp, not a diagnosis
The birth-year snapshot is designed as an on-ramp — a quick, accessible way to encounter WuYun-LiuQi before engaging with the more detailed daily and seasonal tools. It is educational by design. The snapshot describes the climate of a year, not the constitution of a person, and it should never be used to self-diagnose or to make medical decisions. For any health concern, consult a qualified practitioner.