Ba Zhai, the Eight Mansions: Every Kua, Every Direction, and the Rule Behind the Table

The Kua number picks the trigram

The Kua number is a single digit from 1 to 9, never 5, calculated from the birth year and gender, and each Kua is one of the eight trigrams of the Later Heaven bagua — the arrangement that places the trigrams on the compass. The trigram carries an element, a home direction and a group:

The formula uses the last two digits of the birth year, reduced to a single digit. For births before 2000, a man subtracts that digit from 10 and a woman adds 5; for births from 2000 onward, a man subtracts from 9 and a woman adds 6; reduce again if the result has two digits. A result of 5 becomes 2 for a man and 8 for a woman, because there is no fifth mansion — why there is no Kua 5 is a short story about the centre of the Lo Shu square. Two things trip people up. The year is the Chinese solar year, beginning at Li Chun on or about 4 February, so a January birth counts as the previous year. And the formula is deliberately different for men and women, which is classical and intentional rather than an oversight. How to find your Kua number walks the arithmetic with examples, and the Kua calculator does it with the Li Chun boundary handled.

The eight energies

Every one of the eight compass directions receives one of eight named energies, and the names, ranks and jobs are the same for everyone — only their placement changes with the Kua:

Fu Wei is always the Kua's own home direction: a Kua 1 person's Fu Wei is north, a Kua 9 person's is south. The other seven are distributed around it by the rule in the section after the tables. Each energy has its own full entry — Sheng Qi, Tian Yi, Yan Nian, Fu Wei, Huo Hai, Wu Gui, Liu Sha and Jue Ming — for readers who want the texture rather than the table.

The complete table, by Kua

Eight Kua numbers, eight energies, sixty-four cells. This is the whole of Ba Zhai in one grid — every "which way should I face" answer comes from a row of it:

Read across a row and the group structure is already visible: Kua 1's four favourable directions are south-east, east, south and north — the home directions of Xun, Zhen, Li and Kan, the four East-group trigrams — and its four unfavourable are the four West-group homes. Every East-group Kua favours exactly the East-group directions and every West-group Kua favours exactly the West-group directions, which is why the Life Group is the first thing a practitioner asks about a person and a house. Each Kua also has its own page — Kua 1, Kua 2, Kua 3, Kua 4, Kua 6, Kua 7, Kua 8, Kua 9 — with its row read out direction by direction.

The same table, by direction

The question people actually bring to a compass is the reverse one: "the bed can only go with its head to the north — what is north for me?" This is the same sixty-four cells indexed the other way:

Notice that no direction is good for everyone and none is bad for everyone. North is Sheng Qi for Kua 4 and Jue Ming for Kua 2; south-west is the best direction a Kua 8 person has and the worst a Kua 1 person has. Any Feng Shui advice that names a direction without asking who is going to use it is describing a building, not a person — or is not classical Feng Shui at all.

Why those directions: the line rule

The table is not a list someone memorised. Every row is generated from the Kua's trigram by one rule: take the three lines of your trigram, change some of them, and the trigram you get is the direction; which lines you changed is the energy. A trigram has three lines, each solid (yang) or broken (yin), read here from the top down. Changing none, one, two or all three gives exactly eight results — the eight trigrams, the eight directions — and the classical texts assign each pattern of change to one energy:

Run it for Kua 1, the trigram Kan ☵ — broken, solid, broken from the top. Change nothing and you have Kan, north: Fu Wei. Change the top line and you get solid, solid, broken — Xun ☴, south-east: Sheng Qi. Change the middle line and you get broken, broken, broken — Kun ☷, south-west: Jue Ming. Change the bottom line: broken, solid, solid — Dui ☱, west: Huo Hai. Change top and middle: solid, broken, broken — Gen ☶, north-east: Wu Gui. Change middle and bottom: broken, broken, solid — Zhen ☳, east: Tian Yi. Change top and bottom: solid, solid, solid — Qian ☰, north-west: Liu Sha. Change all three: solid, broken, solid — Li ☲, south: Yan Nian. That is the Kua 1 row of the table, reproduced without looking anything up, and the same eight operations produce every other row.

The rule also explains the East–West split, which most sources present as a bare fact. The four favourable patterns — change nothing, change the top, change the middle and bottom together, change all three — always turn a trigram into one of the same four-trigram family, and never into the other family. Start from any East-group trigram and those four operations land only on Kan, Zhen, Xun and Li; start from any West-group trigram and they land only on Qian, Kun, Gen and Dui. The groups are not two lists of numbers that happen to work; they are the two halves the rule cuts the bagua into. The Ba Zhai entry keeps the short version.

Person, house and time

Ba Zhai reads the person. The same eight energies can also be cast from a building, using the trigram of the direction its back faces — its sitting direction — in place of the Kua; that is the house trigram (宅卦) method of the classical texts, and a full Eight Mansions reading lays the occupant's directions over the house's. What Ba Zhai does not contain is time. Which sectors of a house are active this year or this month, where the annual afflictions sit, when a renovation should wait — those come from Flying Stars, a separate method built on the same compass, and how Flying Stars work is the companion to this piece. The finer 64-hexagram reading of a building's axis belongs to a third method again, Xuan Kong Da Gua.

A practitioner uses all three, but they answer different questions, and the mistake in most popular Feng Shui is answering a person question with a building method or a time question with a person method. Ba Zhai's question is narrow and it answers it completely: given who you are, which way should you face?

Using the table

Take a compass reading before anything else — a phone compass held away from steel and taken twice is enough for the eight sectors of 45° each. Then apply the table in the order the tradition weights it: the direction you face at your desk should be Sheng Qi if the room allows it, and any favourable direction if it does not; the head of the bed should point to a favourable direction, with Tian Yi the classical choice for rest; and the front door should ideally face a favourable direction for the main occupant. When the favourable directions are out of reach the rule inverts into an avoidance rule, which is the one that matters most: never face, and never sleep with the head toward, Jue Ming.

Bed direction and your Kua number and the desk that faces your total-loss direction work the two commonest cases in detail. The Kua calculator gives you your row of the table, with the Li Chun year boundary already handled, and the Feng Shui learn hub sets Ba Zhai beside the building and time methods it was always meant to be read with.