Xuan Kong Da Gua: Calculating Sitting and Facing Hexagrams

Sitting vs facing — definitions

The facing direction is where the building faces — usually, though not always, the direction of the main entrance. The sitting direction is the opposite, behind the back wall, and is always the facing turned 180°. For a freestanding house this is unambiguous. For an apartment, the reading is the building’s: the direction its main entrance faces. Stand inside the front door looking out: the bearing ahead of you is the facing. Most beginners take the reading with their back to the door, which gives the sitting instead.

Compass reading methodology

Use a Lou Pan if available. With a Western compass: stand about a metre from the wall (away from metal), hold it level, take three readings a little apart and average them. Then correct for the local magnetic declination — it varies by place and year, often by several degrees, so look up your own latitude and longitude with NOAA's online calculator. The result is your bearing in degrees from true north, and at this precision the correction is not optional.

Translating the bearing into two hexagrams

Divide the facing bearing by 5.625 and keep the whole part: that is the facing hexagram’s segment, counted clockwise from due north (segment 0 is 復, 0°–5.625°; segment 31 is 乾, 174.375°–180°; segment 32 is 姤; segment 63 is 坤). Add 32 for the sitting hexagram — the segment directly behind. Check the result: every line of the sitting hexagram should be the inverse of the facing’s, and the two 卦運 should match. A bearing within 0.9375° (one line) of a segment boundary should be re-measured before the reading is trusted; one sitting exactly on a boundary belongs to both neighbours until a finer reading decides.

References

Canonical sources that inform this guide.

• Feng Shui/Xuan Kong Da Gua/Compass Location · WEBSITE
• Feng Shui/Xuan Kong Da Gua/Binary Representation of the 64 Hexagrams · WEBSITE
• Bagua (Eight Trigrams) · WIKIPEDIA
• I Ching · WIKIPEDIA