Comparison
Saju vs BaZi — same math, different tradition
Saju (Korean) and BaZi (Chinese) are the same divination system mathematically — both derive four pillars of stem-branch characters from a birth moment and interpret them through Five Element theory. The differences are cultural, sub-systemic, and terminological rather than computational.
Saju (사주팔자)
The Korean practice of Four Pillars, systematized in Joseon-era Korea building on Song-dynasty Chinese foundations. Prominent use of Sinsal (神殺, auxiliary stars) and a strong oral-tradition component.
BaZi (八字)
The original Chinese Four Pillars system, attributed to Xu Ziping (10th–11th century). Emphasis on the day master and the ten deities (十神) derived from element relationships between pillars.
Side-by-side
| Axis | Saju | BaZi |
|---|---|---|
| Core calculation | Identical — four stem-branch pairs | Identical — four stem-branch pairs |
| Day master focus | Yes (central) | Yes (central) |
| Five Elements theory | Core | Core |
| Ten Deities (十神) | Used, often lighter emphasis | Heavily emphasized |
| Sinsal / auxiliary stars | Heavy use — 천을귀인, 공망, 역마 etc. | Present but secondary |
| Daeun / Luck cycles | 대운 — same 10-year cycles | 大運 — same 10-year cycles |
| True Solar Time correction | Standard in modern Korean practice | Standard in modern Chinese practice |
| Gender-dependent Daeun direction | Yes | Yes |
| Primary modern context | Life decisions, marriage, business, naming | Business, feng shui integration, life planning |
| Written tradition | Korean + Hanja mixed; oral transmission strong | Classical Chinese texts dominant |
| Relationship to lunar calendar | Uses solar terms (節氣) for pillar boundaries | Uses solar terms (節氣) for pillar boundaries |
The shared mathematical core
Saju and BaZi use the exact same calculation. Given a birth moment, both derive four pairs of stem-branch characters — 天干 (Heavenly Stem) + 地支 (Earthly Branch) — for year, month, day, and hour. The month pillar is indexed to solar terms (節氣 / 절기), not lunar months, so a birth on 2024-02-04 (立春, the start of spring) will have a different year pillar in both systems than 2024-02-03. The day pillar uses the 60-jiazi cycle anchored to a reference date that both traditions share. If a Korean practitioner and a Chinese practitioner compute pillars from the same birth moment, they will get identical results.
Where the traditions diverge
The differences are interpretive, not computational. Korean Saju has historically given heavier weight to Sinsal — auxiliary stars like 천을귀인 (Heavenly Virtue Nobility), 공망 (Void), 역마 (Traveling Horse), and 백호 (White Tiger). These are lookups against the year or day pillar, and a Korean reading will often lead with whether any significant Sinsal land on important pillars. Chinese BaZi readings, especially in the Ziping school, tend to lead with the day master's element state (strong / weak) and the ten-deity distribution, with Sinsal treated as flavor rather than structure. Both are valid; they are different reading styles on the same chart.
Language and terminology
A Saju reading typically uses Hangul terms with Hanja in parentheses — e.g., 정관 (正官, Direct Officer). A BaZi reading uses Classical Chinese, usually with pinyin glosses in English material. When an English-language service says "BaZi" vs "Saju," it usually means the same thing but signals which tradition's interpretive conventions it follows. Multi Fortune's Saju engine is computationally identical whether the user calls it Saju or BaZi; the locale setting affects terminology display, not the math.
Practical equivalence for most users
If you are building software or consulting someone for a reading, the practical question is: whose interpretive school? A Korean tradition reader will emphasize Sinsal; a Chinese Ziping school reader will emphasize day master strength. Neither is more correct — they are different orderings of the same structural facts. The choice is aesthetic and cultural. Someone with strong Korean cultural grounding may find Saju's sub-system vocabulary (귀인, 공망, 삼재) more native than the Chinese equivalents.
Verdict
They are the same system. Pick based on interpretive tradition, not math.
Saju and BaZi compute identical pillars. Saju places heavier weight on Sinsal auxiliary stars; BaZi places heavier weight on day-master strength and the ten deities. Both are valid reading orders. If you are working in Korean cultural context, use Saju terminology; in Chinese context, use BaZi. A multi-system service like Multi Fortune can label either without changing the underlying data.