Zi Wei Dou Shu (Purple Star Astrology) chart calculator
Enter a Gregorian birth date and time to draw the twelve palaces with their main stars, brightness and Four Transformations. The chart is computed in your browser from the open-source engine — the same rules the paid reading on this site uses.
What a Zi Wei Dou Shu chart is built from
A Zi Wei Dou Shu chart is a twelve-palace grid derived from three inputs: lunar birth year, lunar birth month, and birth hour. The year decides where Zi Wei (紫微, the Purple Star) lands and therefore the whole palace sequence; the month and hour decide the Life Palace position; the year stem decides the Four Transformations. Nothing in the chart is random — every placement follows a rule that can be recomputed and checked by hand.
The three inputs, and why the hour matters most
The birth hour fixes the Life Palace (命宫) and the Body Palace (身宫). Moving the hour by one 时辰 (two hours) shifts the Life Palace by one palace and can move the Body Palace to a different position entirely — which is why two charts from the same date but different hours are not variations of the same reading, they are different charts. If the hour is unknown, the chart cannot be drawn from a guess: the Life Palace position is what everything else hangs on.
What the twelve palaces describe
Each palace is a domain of life, not an event: Life (命宫) is the overall pattern, Spouse (夫妻) is how partnership is handled, Career (官禄) is how work is structured, Wealth (财帛) is how money moves, Migration (迁移) is how you appear outside, and the remaining seven cover parents, children, siblings, property, health, friends and fortune. A palace with no main star borrows from the opposite palace (对宫), which is why an apparently empty palace is never actually empty.
Brightness and Four Transformations
Every main star carries a brightness grade in each palace — 庙 (temple, strongest), 旺 (prosperous), 得 (gain), 利 (benefit), 平 (level), 不 (weak), 陷 (fallen). Brightness is positional, not absolute: the same star is strong in one palace and fallen in another. Four Transformations (四化 — 禄 Lu, 权 Quan, 科 Ke, 忌 Ji) are applied by the birth year stem and mark where energy concentrates, where authority sits, where reputation accrues and where friction collects.
Reading order that avoids the common mistakes
- Start at the Life Palace and its triangle (三合): Spouse, Career, Migration. Those four together are the structural read; everything else is detail.
- Read brightness before stars. A fallen star in a strong palace position is a different claim from a strong star in a fallen position.
- Treat Four Transformations as the moving layer, not a verdict. 忌 is friction, not misfortune.
- Do not read a single palace in isolation. A palace is only meaningful against its opposite palace and its triangle.
What this chart does not tell you
A chart describes tendencies and structure, not events. It does not date a marriage, a job change or a loss, and it does not override decisions. The decadal cycles (大限) and yearly cycles (流年) add timing layers on top of this chart, but timing layers describe pressure, not prediction. This calculator draws the natal chart only.
How to verify a chart you were given elsewhere
Enter the same birth date and hour here and compare palace by palace. The engine is open source, so any disagreement can be traced to an input (calendar conversion, hour boundary, true solar time) rather than to a difference of opinion. Most disagreements between charts come from three sources: converting a Gregorian date to lunar with the wrong year boundary (立春 vs lunar new year), treating the 子 hour as starting at 23:00 instead of splitting at midnight, and ignoring true solar time for births far from the standard meridian.