How are the eight characters of saju calculated?
Updated ·
The birth year, month, day and hour each become one heavenly stem and one earthly branch: four pairs, eight characters.
Four pillars, eight characters
Saju (四柱) means four pillars, and palja (八字) means eight characters. The birth year, month, day and hour are each written as one heavenly stem (天干) and one earthly branch (地支), which makes four pairs and eight characters.
There are ten stems, 甲乙丙丁戊己庚辛壬癸, and twelve branches, 子丑寅卯辰巳午未申酉戌亥. Paired in order they form a cycle of 60 that runs through years, months, days and hours.
Year pillar: changes at Ipchun
The year pillar changes at the Ipchun minute. The year 4 CE was a Gapja (甲子) year, so subtracting 4 from the year and taking the remainder after dividing by 60 gives the year's place in the cycle. 2027 is a Jeong-mi (丁未) year.
Month pillar: changes at 12 solar terms
The month pillar changes at 12 solar terms such as Ipchun, Gyeongchip and Cheongmyeong. From Ipchun until Gyeongchip is the Tiger month (寅), from Gyeongchip until Cheongmyeong the Rabbit month (卯), and so on.
The month's stem follows from the year stem. This rule is called Ohodun (五虎遁).
Day pillar: one per day without a break
The day pillar moves one step through the 60-day cycle every day, without restarting at a new month or year. It is found by counting days from a reference date.
SAJUDORIM treats 11 p.m. as the start of the next day, because the Rat hour begins at 11 p.m.
Hour pillar: changes every two hours
The hour pillar works in two-hour blocks: 11 p.m. to 1 a.m. is the Rat hour (子), 1 to 3 a.m. the Ox hour (丑), and so on. Its stem follows from the day stem, a rule called Oseodun (五鼠遁).
If the birth time is unknown, the hour pillar is left empty and the reading uses six characters.
Solar term times, 2000 to 2028
Questions
- What is a manseryeok?
- A calendar that lists the year, month and day pillars for each date. It is a precomputed table of solar term times and the 60-day cycle, and saju calculation rests on it.
- Do people born on the same day have the same saju?
- Not if they were born at different times; the hour pillar differs. It changes every two hours, so births on the same day split into at most twelve hour pillars. On a day when a solar term changes, the month pillar can also depend on the time.