Eight Mansions Feng Shui: Kua Groups & Birth Elements

Eight Mansions (Ba Zhai) is the method behind the calculators on this site. It pairs a person with a home through eight trigrams and eight compass directions. This page explains how the system is built, how your Kua number is worked out, and what "birth element" can and cannot mean.

What Eight Mansions is

Classical feng shui is usually divided into two broad schools. The Form School reads the shape of the land, water and buildings. The Compass School reads directions with the luopan compass. Eight Mansions belongs to the Compass School. Its core idea is matching: a person and a house are each assigned one of the eight trigrams of the bagua, and the directions that suit the trigram are the directions that suit the person.

The method is commonly attributed to the classical text Ba Zhai Ming Jing (八宅明镜). We have not verified this attribution against a primary edition, so treat it as the usual attribution rather than a checked citation.

For a person, the trigram comes from the Kua number (also written Gua), calculated from the birth year and the traditional male or female formula. Each Kua number gives a fixed set of four favorable and four unfavorable directions.

The eight palaces

The eight trigrams sit around the Lo Shu square, a three-by-three grid numbered 1 to 9. The eight outer cells each hold a trigram; the center cell, 5, holds none. That is why there are eight Kua numbers, not nine. The table below is generated directly from the calculator's own data.

East group and West group

The eight Kua numbers split into two groups of four:

• East group (East Four Life): Kua 1, 3, 4, 9.
• West group (West Four Life): Kua 2, 6, 7, 8.

Everyone in the same group shares the same four favorable directions; what differs is the order, meaning which of those four is Sheng Qi, Tian Yi, Yan Nian or Fu Wei for each number. The four favorable directions of one group are exactly the four unfavorable directions of the other. This is why the group matters when two people share a bedroom: partners in the same group can usually find a direction that suits both. The Feng Shui Calculator shows your group and your own order of directions.

How the Kua number is calculated

1. Find the traditional year. The feng shui year starts at Li Chun, around February 4, not on January 1. Someone born in January or early February usually belongs to the previous year.
2. Add the last two digits of that year, and keep adding until one digit remains. Call it S.
3. Apply the formula. Born 1900–1999: male Kua = 10 − S; female Kua = S + 5, reduced to one digit. Born 2000–2099: male Kua = 9 − S; female Kua = S + 6, reduced to one digit.
4. Replace 5. A result of 5 becomes 2 for men and 8 for women.

Worked example: a man born in 1985, after Li Chun. Male, born 1900–1999: Kua = 10 − S. Working: 8 + 5 = 13 → 1 + 3 = 4; 10 − 4 = 6. Result: Kua 6, the Qian trigram, Metal element, West group.

The two formulas differ because Eight Mansions follows yin and yang: the male formula counts down from a fixed number and the female formula counts up, so the same year can give two different numbers. For the step-by-step working, the year table and the exact Li Chun dates, use the Kua Number Calculator.

Birth element: two different ideas

"Birth element" is used for two different things, and it helps to keep them apart:

• Trigram element. Each Kua trigram has an element (the third column of the table above). This is part of Eight Mansions itself, and the calculator shows it with your Kua number.
• Birth-year element. Other traditions give the birth year its own element, for example from the year's Heavenly Stem, or from the Na Yin system of the sixty-year cycle. These conventions can give different answers for the same year, and they are not the same as the trigram element.

On this site: the Feng Shui Calculator shows your Kua trigram element as your element. Because the birth-year conventions disagree, it does not calculate a separate birth-year element, and we do not present any one convention as the correct one.

The Five Elements cycles

The elements (Wu Xing) are Wood, Fire, Earth, Metal and Water. Feng shui uses two cycles between them.

The generating cycle runs Wood → Fire → Earth → Metal → Water → Wood. Each element feeds the next: wood fuels fire, fire leaves ash that becomes earth, earth yields metal, metal collects water, and water nourishes wood. Traditionally an element is supported by the one before it in this cycle.

The controlling cycle runs Wood → Earth → Water → Fire → Metal → Wood. Each element restrains the next: roots break up earth, earth dams water, water puts out fire, fire melts metal, and metal cuts wood. This cycle is used to explain tension between elements, and to choose a softening element in between.

In decoration, these cycles are the reason feng shui talks about colors and materials: green and wood for Wood, red for Fire, yellow and ceramics for Earth, white and metal for Metal, dark blue and water for Water.

Common misconceptions

• "My Kua number is 5." There is no Kua 5: the center of the Lo Shu square has no trigram. A calculated 5 becomes 2 (Kun) for men and 8 (Gen) for women.
• "My lucky directions change every year." In Eight Mansions they do not: your Kua number and its eight directions stay the same for life. What changes each year is the annual Flying Star chart, a different method that can be laid over your directions (see the methodology page).
• "This room is lucky." A direction is favorable or unfavorable for a person. The same corner can be Sheng Qi for one member of the household and Jue Ming for another.
• "East group people must live in East group houses." A matching house is traditionally preferred, but furniture placement inside any house still lets you use your own favorable directions.

Find your own Kua number, trigram and group with the Feng Shui Calculator. The optional full report adds this year's annual Flying Stars over your directions.