64 Hexagrams 六十四卦 Glossary

The complete set of six-line figures of the Yijing, laid out on the luopan as a 64-sector ring for hexagram-based feng shui schools.

Liùshísì guà · 六十四卦 (simplified) · 六十四卦 (traditional)

Source credibility (S/A/B/C/X): A    Rule computability (A/B/C): A for the ring geometry as a parameterised plate; the yao-level degree value is a derived figure, unverified

What it is

The Yijing's 64 hexagrams — six-line figures built from the eight trigrams （八卦） — appear in feng shui not as an oracle but as a fine-grained compass ring. On the San Yuan plate, a hexagram ring （六十四卦層） divides the 360° circle into 64 sectors. In the common plate system each hexagram therefore spans 5.625°; a second plate system divides it into 6° sectors, and the two systems must not be mixed. The ring serves the Xuan Kong Da Gua （玄空大卦） school, which reads sittings and facings directly as hexagrams and manipulates them by line exchange （抽爻換象）.

Going one level deeper, the 64 hexagrams contain 384 lines （爻）, which in the 5.625° system would span about 0.9375° each. That figure is a derived division, not a value attested in a classical source — the project marks it unverified and does not present it as a traditional constant. Precision at this scale also exceeds what any handheld compass can resolve (see the measurement limits).

School differences

The hexagram ring belongs to the San Yuan side of the family: it is a San Yuan plate feature, absent from the San He plate's required rings, whose essentials are the three needles, the dragon rings and the 28-mansion scale (see Luopan and San Yuan vs San He). Even within San Yuan, the Da Gua hexagram method is a specialist branch — Jiang Dahong's line transmitted the flying stars, and the hexagram-ring schools developed as a parallel reading of the same classics. Where plate systems disagree (5.625° vs 6°), the project implements both as a parameter rather than declaring one authentic: School Dispute Register for the method.

How this engine computes it

• The 64-hexagram ring is implemented as a parameterised plate system: 5.625° per hexagram or 6° per hexagram, selected explicitly, never mixed within one chart.
• Hexagram lookup is closed-form arithmetic from the ring sector; hexagram-to-trigram composition is kernel data shared with the Eight Mansions module.
• The 384-yao degree value (≈0.9375°) is treated as a derived figure — computed on demand and labelled as derived, not quoted as a classical constant.
• Like all ring-based output, hexagram readings carry the angular uncertainty of the input measurement; a boundary-sector reading is flagged, not resolved silently.

Related entries

Luopan · 24 Mountains · Xuan Kong Flying Star · Nine Stars

Back to the glossary index.