Korean Saju (Four Pillars) Calculator

Turn a birth date and time into a precise Korean Saju (사주 / BaZi) chart — deterministic, astronomically grounded, no LLM guesswork. Returns the four pillars plus five elements, ten gods, sinsal, and luck cycles as clean structured JSON.

Large language models are unreliable at this exact task — computing the ganzhi calendar, solar-term boundaries, true solar time, and lunar leap months. This Actor does it correctly, using real astronomical calculation (Meeus algorithms), so agents and apps can offload it with confidence.

What it does

• 🎴 Four Pillars (연·월·일·시주) — heavenly stems, earthly branches, hidden stems
• 🌗 True solar time correction — longitude + equation-of-time, historical Korea timezones (incl. 1908/1954 offsets, DST periods)
• 🔮 Full analysis — five elements (오행) %, ten gods (십성), strength (신강/신약), useful god (용신), interactions (형충회합), sinsal (신살)
• 📅 Luck cycles — great luck (대운), yearly (세운), monthly (월운)
• 🌙 Solar & lunar input — including leap months
• 🧮 Deterministic — same input, same output; correctness is the moat, not an LLM

How to use

Provide the birth details; get the full chart back as a dataset item.

{
  "calendar": "solar",
  "y": 1990, "m": 5, "d": 16,
  "hour": 9, "minute": 30,
  "gender": "F"
}

Input

Field	Type	Description
calendar	enum	solar (default) or lunar
y m d	integer	Birth year (1900–2100), month, day
hour minute	integer	Birth time, 24h (default 0)
gender	enum	M or F (sets luck-cycle direction)
isLeap	boolean	Lunar leap month (음력 윤달)
longitude	integer	Birthplace longitude for true-solar-time (default 127 ≈ Seoul)

Output

A dataset item with the full chart:

{
  "출생": { "입력": "...", "진태양시": "09:02 (경도보정 −32분 · 균시차 +4분)" },
  "명식": { "일간": "辛(음금)", "연주": { ... }, "월주": { ... }, "일주": { ... }, "시주": { ... } },
  "분석": { "오행": [...], "십성": [...], "신강약": {...}, "용신": "토(土)", "신살": [...] },
  "대운": { ... }, "세운": { ... }, "월운": [ ... ]
}

Pricing

Pay per event — $0.03 per successful calculation. Failed inputs are not charged.

Use cases

• Power a saju / fortune-telling app with an accurate calendar engine (no reimplementation)
• Give an AI agent a reliable tool for Korean birth-chart data instead of hallucinating pillars
• Generate structured saju data for research, content, or personalization

FAQ

Why not just ask an LLM? LLMs routinely get ganzhi, solar-term boundaries, true solar time, and leap months wrong. This is deterministic astronomical computation.

What range is supported? Lunar↔solar conversion is reliable for 1900–2100.

Is the output in Korean? Yes — the chart uses standard Korean myeongri terminology (한자 + 한글). Downstream translation/narration is up to the caller.