Zi Wei Dou Shu Calculator: Free Chart, How to Read It, and Zi Wei vs BaZi

Updated 2026-09-13

A Zi Wei Dou Shu calculator places fourteen major stars and their assistants into twelve palaces from your lunar birth date and hour, then lays out decade and annual limits; the chart is deterministic and checkable. To read it, start with the life palace, the four transformations of your birth year and the current decade limit. Zi Wei and BaZi are two views of the same birth moment, and the classical rule is to trust what both agree on.

What Zi Wei Dou Shu is

Zi Wei Dou Shu, sometimes translated as Purple Star Astrology, is one of the two major Chinese natal systems alongside BaZi. Where BaZi describes a person through five-element balance, Zi Wei paints twelve domains of life as palaces, each holding stars whose brightness and combinations describe that domain. It is prized for detail: career, marriage, property and health each get their own palace.

Anatomy of the chart

Twelve palaces: life, siblings, spouse, children, wealth, health, travel, friends, career, property, fortune and parents. The life palace is set from the lunar month and birth hour, and the others follow in order.
Fourteen major stars: Zi Wei, Tian Ji, Tai Yang, Wu Qu, Tian Tong, Lian Zhen, Tian Fu, Tai Yin, Tan Lang, Ju Men, Tian Xiang, Tian Liang, Qi Sha and Po Jun, placed by the five-element bureau and the lunar day. Dozens of assistant and minor stars follow by further rules.
Four transformations: each year stem sends one star into Lu (prosperity), one into Quan (power), one into Ke (recognition) and one into Ji (obstruction). The birth-year transformations mark the chart's lifelong themes.
Brightness and opposite palaces: a star's strength varies by palace, and each palace is read together with the one opposite it.

Decade limits and annual limits

Time is read through limits. The decade limit moves through the palaces ten years at a time, starting at an age set by the five-element bureau, so the palace lit up in your thirties differs from the one in your forties. The annual limit is the palace for the current year, and each year's stem also sends out its own four transformations, overlaid on the birth chart. A 2026 reading therefore looks at the decade palace, the annual palace and the Bing-year transformations together.

Zi Wei vs BaZi

	Zi Wei Dou Shu	BaZi
Input	Lunar date and hour	Solar-term date and true solar hour
Building block	Stars in twelve palaces	Stems and branches in four pillars
Strength	Detailed portrait of each life domain	Structure, useful god, rhythm of luck
Timing	Decade and annual limits, flying transformations	Luck pillars, annual and monthly pillars
Needs birth hour	Yes, to set the life palace	Preferred; three pillars still readable without it

Why chatbots struggle, and the star-and-pillar cross-check

Casting a Zi Wei chart means converting the Gregorian date to the lunar calendar, handling leap months, deriving the bureau from the life palace stems, and applying a long list of placement rules for major, assistant and minor stars. A general chatbot recalls fragments of these rules and improvises the rest, so its Zi Wei charts often misplace the life palace or the Zi Wei star and shift between windows.

On Suan (suan.you) the engine casts the chart, the AI only interprets: Zi Wei Dou Shu is placed by rule with birth-year transformations and decade and annual limits, and a destiny reading cross-checks it against BaZi, the classical star-and-pillar method. The verdict cites where the life palace star and the day master agree and says uncertain where they do not.