Tool · Korean four pillars
Saju Calculator (사주)
Saju (사주) — saju-palja, 사주팔자 — is the Korean name for the Four Pillars of Destiny. It is not a separate system: it is the same eight characters, built from the same sexagenary cycle, with the same 立春 / 입춘 year boundary. Enter a birth date and this calculator prints your four pillars under that name.
The short version
There is no such thing as a “Korean answer” that differs from the Chinese one for the same moment on the same time basis. What differs is the clock the birth time was recorded on — and Korea has changed its clock more often than most countries.
This page runs the same engine as every other tool here. We did not write a second calculator for saju, because saju is not a second system.
Your four pillars (사주)
Free · no sign-up
One pair for the year, month, day and hour of birth. The date alone reaches the first three; the hour pillar needs a birth time — and, for a Korean birth, the era matters.
How it’s calculated
- 1
Fix the moment, not just the date
The engine converts your local clock reading into the astronomical instant it names, using the time zone that was actually in force where and when you were born — including daylight saving, which Korea observed in 1948–1951, 1955–1960 and 1987–1988.
- 2
Anchor the year and month to solar terms
The year pillar turns at 立春 / 입춘, the astronomical instant around 3–5 February — not at 설날 and not on 1 January. The month pillar turns at each of the twelve 节 / 절기.
- 3
Name each pillar and read it against the day master
The day stem — 일간, ilgan — is the anchor. Everything else is classified against it: the ten gods 십신, the element tally 오행, the useful god 용신. These are the same tables a Chinese reading uses, under Korean names.
The full rule set — every convention, in order, with the engine field names — is published on the methodology page.
What a saju calculator actually computes
Four pillars — year, month, day, hour — each written as a heavenly stem over an earthly branch: 천간 cheongan over 지지 jiji. Four pairs, eight characters, hence 사주팔자. That is the whole output of the computation, and everything a reading does is done on top of it.
The computation is arithmetic, not interpretation. The day pillar advances one pair per calendar day on a continuous count; the year pillar advances at 立春; the month pillar at each solar term; the hour branch is fixed by the time of day and the hour stem follows from the day stem by the five-rat rule, 오서둔. Given the same input and the same time basis, every correct calculator must produce the same eight characters.
That is why we can say something unusually direct: if a saju calculator and a BaZi calculator disagree about your chart, at least one of them has mishandled the input. The system does not have room for a Korean variant of the arithmetic.
Saju and BaZi are one system with two vocabularies
The discipline is called 명리학 myeongrihak — the study of the logic of destiny — and its terms are Chinese, pronounced in Korean: 십신 for 十神, 용신 for 用神, 대운 for 大運. Korean readings are usually quoted by the day stem, “I am a 甲木 ilgan”, which is the same anchor we build the ten gods around.
Practically, the traditions even used the same social machinery. A groom’s family sent birth data — 사주단자 — and a reader assessed 궁합 before a betrothal; under the Joseon court, calendar and fate work was administered by a royal bureau, 관상감, and examined in the state’s own tests.
So when people search for “BaZi vs saju”, the honest answer is that there is no rivalry to resolve. The differences are vocabulary, which changes how a reading sounds but not what it computes — and the clock, which does change the answer.
Where the answer really does change: the clock
Korea has not always run on the same clock. From 1908 to 1911 the country was on UTC+8:30, on the 127°30′E meridian; from 1912 it moved to UTC+9 and 135°E; in 1954 it went back to UTC+8:30 until 1961; and since 10 August 1961 it has been UTC+9. On top of that, daylight saving was observed in 1948–1951, 1955–1960 and 1987–1988.
This is the origin of the traditional instruction to subtract 30 minutes from a Korean birth time. That half hour is exactly the gap between the current standard meridian, 135°E, and the one the country used in 1908–1911 and again in 1954–1961: 7.5° × 4 minutes = 30 minutes. It is not a rounding of Seoul’s longitude.
It is a useful constant and an imprecise one. The exact longitude term depends on where in Korea you were born — roughly −32 minutes in Seoul, −24 in Busan, −35 in Mokpo — and the equation of time adds a seasonal swing of about −14 to +16 minutes on top. A flat 30 minutes is roughly right in spring and autumn and off by half an hour in late winter.
- Give the recorded wall-clock time and the city, not a time you have already corrected yourself.
- If the birth falls in a daylight-saving window, say so — an hour is one whole hour pillar.
- For a birth between 1954 and 1961, expect the longitude term to be small: the clock was close to the peninsula’s own meridian.
The year starts at 입춘 — not at Lunar New Year
Korean and Chinese readers agree on this, and both spend time correcting the popular version. The year pillar changes at 立春 / 입춘; the animal you grew up with comes from Lunar New Year, 설날. For most of the year the two coincide. In the week or two between them they do not, and the folk animal and the year branch name different animals.
Neither is wrong. They are answering different questions — one is a cultural shorthand, the other is what the chart is actually built on. This calculator shows the year pillar, because that is the one that participates in the reading.
What the four pillars are not
They are not a forecast. The eight characters are a description of a moment on a calendar — the same eight for everyone born at the same instant in the same place. Two people can share a chart and live different lives; the chart did not fail, it was never a prediction.
They are also not a personality quiz, and the element tally is not a score out of 100. The moment a count is weighted by season or month, you are no longer looking at a fact about the chart — you are looking at one school’s model of it. We show the raw tally and label it as the raw tally.
What the pillars are is a precise, reproducible, checkable piece of arithmetic — and the honest part of any reading is that you can verify it yourself, which is exactly what the sections below let you do.
A worked example
The same worked case used across this site — 4 February 1990, 10:00, Taipei — so you can cross-check one page against another. The engine version is printed on the result: run the same input on any v1.1.0 build and you should get the same eight characters.
Input
- Date
- 4 Feb 1990
- Time
- 10:00
- Place
- Taipei, Taiwan
- Time zone
- Asia/Taipei
Nearest 节
Next: 立春, 4 Feb 1990 10:14Birth at 10:00 — 14 minutes before the year boundary.
Year 年
己巳
Jǐ Sì
- Stem
- 己 · 土
- Branch
- 巳 · Snake
- 纳音
- 大林木
Month 月
丁丑
Dīng Chǒu
- Stem
- 丁 · 火
- Branch
- 丑 · Ox
- 纳音
- 涧下水
Day 日
庚子
Gēng Zǐ
- Stem
- 庚 · 金
- Branch
- 子 · Rat
- 纳音
- 壁上土
Hour 时
辛巳
Xīn Sì
- Stem
- 辛 · 金
- Branch
- 巳 · Snake
- 纳音
- 白蜡金
Why this page is not a separate calculator
This tool renders the identical four-pillar view as the stems-and-branches page, because there is nothing to fork: saju is 四柱, and 四柱 is what the engine computes. Building a second calculator with “Korean settings” would have been a marketing decision dressed up as a technical one — and it would have given two different answers to the same question, which is the one thing a calculator may never do.
Engine v1.1.0 · these eight characters, this tally — reproduce them any time from the same input.
The Korean vocabulary
Saju uses the Chinese terms, pronounced in Korean. If a reading sounds unfamiliar, this table is the whole translation layer — the mechanics underneath are the ones on every other page of this site.
- 사주四柱sajuThe four pillars
- 사주팔자四柱八字saju-paljaThe four pillars and eight characters
- 천간天干cheonganHeavenly stems — the surface characters
- 지지地支jijiEarthly branches — the roots, with hidden stems
- 오행五行ohaengThe five elements
- 일간日干ilganThe day master — the chart’s reference point
- 십신十神sipsinThe ten gods
- 용신用神yongsinThe useful god
- 대운大運daeunThe ten-year luck pillars
- 세운歲運seunThe annual pillar
- 궁합宮合gunghapCompatibility between two charts
- 입춘立春ipchunBeginning of spring — the BaZi year boundary
- 절기節氣jeolgiThe solar terms
- 명리학命理學myeongrihakThe technical name of the discipline
Korea’s clocks, 1908 to today
This is the one place where Korean saju genuinely differs from Chinese BaZi — and it is civil law, not astrology. The standard meridian decides the longitude term in the true solar time correction, so a birth from a different era needs a different correction.
- 1 Apr 1908 – 31 Dec 1911UTC+8:30127°30′E
- 1 Jan 1912 – 20 Mar 1954UTC+9135°E
- 21 Mar 1954 – 9 Aug 1961UTC+8:30127°30′E
- 10 Aug 1961 – presentUTC+9135°E
Korea also ran daylight saving in 1948–1951, 1955–1960 and 1987–1988 — an hour ahead of the offset in force for part of each year. Births inside those windows need an hour removed before any pillar is computed; the engine does this automatically and prints the deduction as its own line on the result.
Questions
- What is a saju calculator?
- It is a calculator for the Four Pillars of Destiny — 사주, saju — the Korean name for the same system known in Chinese as BaZi (八字). It converts a birth date, time and place into four stem-and-branch pairs: 천간 over 지지 for the year, month, day and hour. The computation is identical regardless of which name you use for it.
- Is saju the same as BaZi?
- Yes, structurally. Same sexagenary cycle, same 立春 / 입춘 year boundary, same day master, same ten gods, same useful god, same ten-year luck pillars. The differences are the vocabulary and the clock conventions of the country you were born in.
- Why do Korean readings subtract 30 minutes from the birth time?
- Because Korea’s clock runs on the 135°E meridian while the peninsula sits around 127.5°E — and 7.5° × 4 minutes is exactly 30 minutes. It is the gap between today’s standard meridian and the one Korea used in 1908–1911 and 1954–1961, so it is a convenient constant rather than an exact correction.
- Do I need my exact birth time for a saju chart?
- Only for the hour pillar. The year, month and day pillars come from the date alone, because they are anchored to solar terms rather than to the clock. Without a birth time you still get six of the eight characters, the day master and the element tally — but the hour pillar, and the hour-dependent part of any reading, stays open.
- I was born in Korea in the 1980s. Does the clock history change my chart?
- Only if you were born inside a daylight-saving window — in 1987 and 1988, from May to October. Outside those windows your clock was already on standard time. Inside one, the recorded time is an hour ahead of standard time and that hour has to come off before the pillars are computed. The engine does this automatically and shows the deduction.
Next
Stems and branches reference
The ten stems, twelve branches, hidden stems and the full sixty-pair cycle.
OpenTrue solar time calculator
Every correction term printed separately — longitude, equation of time, and daylight saving.
OpenGuide: what is saju?
The full explainer — vocabulary, Korea’s clock history, and a worked Seoul example.
OpenFull chart
Get your own four pillars
The calculator is free and needs no account. It shows all four pillars, hidden stems, ten gods, your element balance and ten-year luck cycles — with the engine version on the result.
BaziPattern provides AI-generated readings for entertainment and cultural exploration purposes only. Readings are not predictions, or medical, legal, or financial advice.