Four Pillars (Saju) Almanac
Draws the four pillars for a birth moment from the solar terms and the sexagenary cycle, counts the five elements and names the ten gods against the day stem, with the true-solar-time correction for the hour pillar.
A 사주 chart is a birthday written in another calendar: four pairs from the sexagenary cycle for the year, month, day and two-hour block of a birth. Drawing it correctly is astronomy — the month pillar turns on a solar term and the year pillar turns at 입춘, not at New Year — and that part of this page is exact and checkable. The reading beside it is classical 명리 tradition, quoted with the book it comes from.
Birth moment
Leave it empty if it is unknown
True solar time (진태양시)
Korea keeps the mean solar time of 135°E, and nowhere in Korea is at 135°E — Seoul is eight degrees west of it, so the sun crosses the meridian about 32 minutes after the clock says noon. The equation of time adds up to another ±16½ minutes depending on the date. Together they can move a birth into the neighbouring 시지.
The four pillars
| 시주 · hour | 일주 · day· the reference | 월주 · month | 년주 · year | |
|---|---|---|---|---|
| 천간 | 癸계 | 乙을 | 辛신 | 庚경 |
| 지지 | 未미 | 亥해 | 巳사 | 午오 |
| 십신 (stem) | 편인 | — the reference | 편관 | 정관 |
| 십신 (branch) | 편재 | 정인 | 상관 | 식신 |
| 지장간 | 정 을 기 | 무 갑 임 | 무 경 병 | 병 기 정 |
- The month pillar turns on a 절, not on the first of the month. This birth falls in the month opened by 입하(立夏) at 1990-05-06 03:36.
- The next term is 소만 at 1990-05-21 16:37.
- The year pillar counts from 입춘. This birth sits in the 간지 year 경오, which began at 입춘 1990.
- Lunar birthday: 1990, month 4, day 16.
오행 — the five elements
- 목 · wood1(3)
- 화 · fire2(6)
- 토 · earth1(5)
- 금 · metal2(3)
- 수 · water2(3)
The left number counts the visible characters — four stems and four branches. The right one adds every stem hidden inside a branch, which is why it is always larger.
십신 — the ten relations
비겁
0
식상
2
재성
1
관성
2
인성
2
Every character except the day stem is named by how it stands to the day stem. The day stem itself is the reference and has no relation to itself.
What the tradition says
Day stem — 을(乙) (wood)
Wood as the day stem is read in the classical texts as growth that keeps a direction: something that goes on rising and does not easily bend out of its line. 갑 is the standing tree, 을 the vine that reaches around an obstacle rather than through it.
A 음 stem, which the texts describe as gathering and responding.
The month it was born in
Born in a summer month (사·오·미, from 입하). 『궁통보감』 reads summer births as fire at its height, and asks first whether the chart has water to keep it from running dry.
The balance of the five elements
- wood appears once and thinly. Traditionally this is read as a quality present but not relied on.
- fire sits at about its even share. 『적천수』 calls a chart where no element overwhelms the rest 중화 — balanced — and treats that, not abundance, as the good case.
- earth appears once and thinly. Traditionally this is read as a quality present but not relied on.
- metal sits at about its even share. 『적천수』 calls a chart where no element overwhelms the rest 중화 — balanced — and treats that, not abundance, as the good case.
- water sits at about its even share. 『적천수』 calls a chart where no element overwhelms the rest 중화 — balanced — and treats that, not abundance, as the good case.
The ten relations
No one 십신 group stands out. The classical texts read an even spread as 중화, and treat it as the unremarkable good case rather than as a lack of character.
Nothing in the chart falls in 비겁. Traditionally read as a register the chart has no character of its own for.
Where the readings come from
- 『연해자평(淵海子平)』, compiled by 서승, Ming — the text that fixed reading a chart from the day stem, and the source of the 십신 names.
- 『자평진전(子平眞詮)』, 심효첨, 1776 — the systematic treatment of the 십신 groups used above.
- 『적천수(滴天髓)』, attributed to 유기 with 임철초’s commentary — the source of 중화, balance as the thing a chart is read for.
- 『궁통보감(窮通寶鑑)』 (난강망) — 조후, the seasonal reading of a day stem by the month it was born in.
- 『오행대의(五行大義)』, 소길, Sui (c. 600) — the earliest systematic account of 상생 and 상극.
- The 절기 instants come from the sun’s apparent longitude, computed with the abridged VSOP87 series in Meeus, *Astronomical Algorithms* 2nd ed., ch. 25 and Appendix III; the equation of time is ch. 28, formula 28.3.
How to use it
Enter the birth date and time
The date is the solar (Gregorian) one. If the birth time is unknown, tick the box: the hour pillar is then left out rather than defaulted to midnight, which would print a 자시 that changes every two hours at random.
Decide about true solar time
Korea runs on the mean solar time of 135°E and no part of Korea is at 135°E, so the sun is about half an hour behind the clock — plus or minus the equation of time, which swings ±16½ minutes over the year. The switch is off by default because practitioners disagree about it, and the page shows both the clock time and the solar time so you can see whether it moved the 시지 at all.
Read the pillars against the term that opened the month
Under the chart the page names the 절 that opened the month pillar and the instant it fell, to the minute. That is the number to check against a printed 만세력 if two of them disagree about your chart — nine times out of ten the disagreement is a birth within a few hours of a 절입시각.
Then read the description, knowing what it is
The 오행 counts and 십신 are bookkeeping over the eight characters and are exact. The paragraphs under them are what 『연해자평』, 『자평진전』, 『적천수』 and 『궁통보감』 say about those shapes, each named. They describe a pattern of characters, not a person, and they forecast nothing.
Common questions
Why is my year pillar different from my 띠?
Because they may count from different days. 명리 turns the year at 입춘, folk usage often turns it at 설날, and school textbooks use 1 January. A birth in January or early February can therefore be three different animals depending on who is asked. The 띠·별자리 page shows all three side by side; this page uses 입춘, because that is the boundary a 만세력 uses.
Should I turn on true solar time?
There is no settled answer, which is why it is a switch. The 만세력 tradition predates standard time, so one school reads the sun; another holds that the recorded clock time is the datum because that is what the record says. Turn it on and look: if the panel says the 시지 did not move, the question is moot for your chart.
How accurate are the solar-term times?
They come from the sun’s apparent longitude computed with the abridged VSOP87 series in Meeus, *Astronomical Algorithms*, and they agree with 한국천문연구원’s published 절입시각 to within a minute across every term of a year. The test suite checks all twenty-four terms of 2026 to the minute and the twelve 사주 months of 2024 and 2025.
Does this predict anything?
No. The chart is a date conversion and the description is a quotation from four books written between the Song dynasty and the eighteenth century. There is no evidence that a birth moment predicts a life, and this page does not claim one. It is here because 만세력 arithmetic is genuinely interesting and almost every site that prints it gets the 절기 boundary wrong.
Is my birth date sent anywhere?
No. The whole computation — the solar longitude series included — runs in your browser, and nothing is stored.
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