Building a Zi Wei Dou Shu Chart: Palaces, Bureau and Star Placement
A Purple Star chart is not drawn by intuition. It is computed, step by step, from four pieces of data: the year, the month, the day and the hour of birth, all read in the Chinese calendar rather than the Gregorian one. Where a BaZi reading turns those four values into eight characters and looks at how they relate, Purple Star Astrology uses them to place a fixed name — a star — into each of twelve seats.
This article sets out the logic of that construction in the order the steps are performed: the frame of twelve branches, the Life palace that anchors the chart, the Five Elements Bureau that gives it its pace, and the placement of the stars themselves. The arithmetic is deliberately left out — it is mechanical, it is long, and it is exactly the kind of work a Purple Star calculator does without error. What matters for reading a chart is knowing what each step is for.
1. The frame: twelve branches, twelve palaces
The chart is a square divided into twelve cells, and the cells are the twelve Earthly Branches in their fixed order, from the Rat (子) around the ring to the Pig (亥). The branch of a cell fixes several things at once: its compass direction, its element, and its hidden stems — the same properties the Earthly Branches carry in a BaZi chart. Nothing in Purple Star Astrology invents a new geography; it lays a new layer of meaning over the one the calendar already provides.
Each cell becomes a palace (宮, gōng), and a palace is simply a sphere of life that has been given a seat in the grid. A chart is therefore read as twelve places, one for each major domain of a life, with the branch underneath each one supplying its direction and element.
2. The Life palace from month and hour
The step that makes each chart individual is deciding which branch the Life palace (命宮, mìnggōng) occupies. It is fixed by the birth month and hour, taken together; the pair moves the Life palace around the ring, which is why two people born on the same day but at different times receive different charts, and why the hour of birth is as important here as in BaZi.
Two palaces are placed from that pair. The Life palace is the seat of the person themselves — character, fundamental direction, the "I" of the reading. The Body palace (身宮, shēngōng) is a second marker, set from the same month and hour but counted differently; where the Life palace describes what a person is, the Body palace is usually read as where their life energy concentrates as they grow older.
Once the Life palace is fixed, the remaining eleven palaces are laid down in an unchanging sequence around the frame. The order never varies — Siblings, Spouse, Children and so on — so the only thing a birth date decides is where the sequence begins. The twelve palaces have their own article; here it is enough to know that the frame is fixed and the starting seat is not.
3. The Five Elements Bureau
The Life palace does not sit on a bare branch. Each branch is paired with a Heavenly Stem in the sixty-part cycle, and the stem for the Life palace is drawn from the birth year. That pairing gives the Life palace a full stem-and-branch pair, and from that pair the classical texts take its Na Yin (納音, nà yīn), the "received sound" element of the sexagenary cycle.
That element is the chart's Five Elements Bureau (五行局, wǔxíng jú) — the one word that describes the pace and texture of the whole chart. There are five bureaus, each named for its element and a number:
| Bureau | Element | Number |
|---|---|---|
| Water Two | Water | 2 |
| Wood Three | Wood | 3 |
| Metal Four | Metal | 4 |
| Earth Five | Earth | 5 |
| Fire Six | Fire | 6 |
The bureau is the chart's time signature in two senses. It sets the age at which the first ten-year limit begins, and it governs the placement of the central star, Ziwei, from the lunar day. A Water Two chart reads at a different tempo from a Fire Six chart, and the difference starts here.
4. Placing the stars
With the frame, the palaces and the bureau in place, the stars can be distributed. The order is fixed.
Ziwei first. The position of the star 紫微 Ziwei is derived from the bureau and the lunar day of birth. It is the anchor of the whole chart: the system is named for it because where it lands, the rest of its group follows.
Tianfu mirrored. The leader of the second group, 天府 Tianfu, is placed from Ziwei by a fixed reflection rule, and the eight stars of its group follow at set intervals.
The rest by their own rules. The fourteen major stars are the skeleton. Around them sit the supporting stars, placed from the year stem and branch, the month and the hour, and the Four Transformations, assigned to stars by the Heavenly Stem of the birth year.
Nothing is left to choice. Every star has exactly one rule and one home in a given chart.
5. Reading positions: the trine and the opposite
A palace is never read alone. Each one is read together with the two palaces that stand a third of the way around the ring from it — its trines — and with the palace directly opposite. This set of three-positions-and-one-opposite (三方四正, sān fāng sì zhèng) is the basic unit of interpretation.
For the Life palace the arrangement is particularly clear. Its trines are the Wealth and Career palaces, and its opposite is the Travel palace. The reading of a person, in other words, is built from what they earn, what they do, and how they appear to the world — not from the Life palace in isolation. The same logic applies to every other palace, which is why the grid is read as a whole rather than cell by cell.
6. Why the rules live in the calculator
Every step above is deterministic: the same birth data always produces the same chart, and no judgement enters until the stars are interpreted. That is precisely why a chart is best cast by tool rather than by hand. The Zi Wei Dou Shu calculator performs the placement and shows the finished twelve-palace chart; the articles in this section explain what the resulting chart means.
Do I need my exact hour of birth?
Yes. The hour is one of the two values that fix the Life palace, so a chart cast from the wrong hour places the palaces in the wrong seats and the whole reading shifts. Where the hour is unknown, the classical fallback is to cast the alternative charts for the candidate hours and to read them against events that are already known.
Is the solar or the lunar calendar used?
The chart is built from the Chinese lunar calendar, with the month and day and the hour all taken from the traditional reckoning. The year stem and branch come from the solar-year boundary in the same way they do in BaZi, which is why the Chinese calendar matters to both systems.
What is the Body palace for?
The Body palace is a second marker placed from the birth month and hour. Where the Life palace describes the person as they are, the Body palace is commonly read as where the life settles and concentrates later on. Schools differ on how much weight to give it, and where they do, the reading says which school it follows.
Why does the same star mean different things in different charts?
Because a star is read through the palace it occupies and the transformations laid on it. The same star in the Wealth palace speaks about earning, and in the Spouse palace about partnership. The palace, not the star alone, is the unit of meaning — which is why the twelve palaces are learned before the stars.
The order of the construction is also the order of a reading. A practitioner checks the frame, finds the Life palace, notes the bureau, and only then looks at stars — because a star without a palace and a bureau is a name with no address.
