Saju (사주): What Korean Saju Is
and How It Differs from BaZi

Someone searches for "saju calculator," lands on a form with fields for date, time and "lunar or solar," and gets a handsome spread of eight characters. A minute later they wonder whether they've stumbled onto some special Korean magic, separate from the Chinese BaZi they read about somewhere. They haven't. The eight characters on the screen would be exactly the same if they had calculated them in Beijing, in New York or in Seoul.

The difference between "saju" and "BaZi" isn't in the math. It's in the language, in local habits, and in what Koreans like to read out of a finished chart. Below: where everything matches, and where the differences are real.

You can calculate a saju chart in our BaZi calculator too: the eight characters are the same, and the table also shows the Ten Gods and the Luck Pillars.

1 What the word "saju" means

Korean 사주 (saju) is the Korean reading of the Chinese characters 四柱 (sì zhù, "four pillars"). The full form is 사주팔자 (saju palja), written 四柱八字: "four pillars, eight characters." The second half of that name is the very same 八字 (bā zì, "eight characters") that this site calls BaZi.

So "saju" and "BaZi" are two names for one thing in two languages, like "Peking" and "Beijing." The Korean study of these charts is called 명리학 (myeongnihak, 命理學, "the study of destiny"). Koreans borrowed the system from China many centuries ago and have developed it their own way since, but the foundation stayed Chinese: four pillars, ten heavenly stems, twelve earthly branches, five elements.

2 How the chart is calculated: nothing Korean, nothing Chinese

Each of the four pillars (year, month, day, hour) has two characters: a heavenly stem 天干 (tiān gān) on top and an earthly branch 地支 (dì zhī) below. In Korean they're 천간 (cheongan) and 지지 (jiji). There are ten stems and twelve branches, and together they make what we call the eight characters. The central character of the chart is the stem of the Day Pillar. In Korean practice it's called 일간 (ilgan, 日干); here we call it the Day Master (日主, rì zhǔ).

Months in the chart follow the solar seasons; the lunar calendar and the day of the month have nothing to do with it. The boundaries are set by the 節氣 (jié qì, "solar terms"), for example 立春 (lì chūn, "Start of Spring"; in Korean 입춘, ipchun). So someone born on February 2 usually still belongs to the previous year in their chart. The same rule applies in Korea.

This is where the most common confusion starts. Korean sites ask for 음력 or 양력 (eumnyeok / yangnyeok), a lunar or a solar date. That's just an input format: a person may remember their birthday by the lunar calendar their grandmother used, and the form converts the date to the ordinary one. The pillars are then built on the solar seasons, as everywhere else. The reference tables Korean practitioners use to check pillars are called 만세력 (manseryeok, 萬歲曆, "the ten-thousand-year calendar"). It's the same thing as the Chinese reference almanac, just in Korean.

3 A glossary: Korean, hanja, and the terms used here

Reading a Korean article on saju, you meet familiar things under unfamiliar names. Hanja (漢字) are the same characters as in Chinese; only the reading differs. Here are the correspondences you'll meet most often.

Two notes on the table. First, in Korea 七殺 is usually called 편관 (pyeongwan), the "indirect officer." That name is also Chinese and appears in old Chinese texts; it simply became the main one in Korea, while Chinese readings more often write 七殺. Second, English-language books and apps don't agree on the names either: 比肩 shows up as Friend, Companion or Shoulder to Shoulder, and 印 as Seal or Resource. They're all translations of the same ten positions; more on them in The Ten Gods of BaZi.

4 Where Korean practice really is different

Everything above is about the math, and the math has no differences. The differences show up as habits: what Korean practitioners do with the input data and what they like to read in a finished chart. There are six such points, and the first two are about time.

The local time correction

Korea runs on UTC+9, which is solar time on the 135° E meridian. Seoul lies at roughly 127° E, so its local solar time runs about 30 minutes behind the clock. Korean practitioners usually subtract those thirty minutes from the time on the birth certificate. On top of that, in 1987 and 1988, around the Seoul Olympics, Korea used daylight saving time (an extra hour from May to October), and that gets subtracted too.

The principle here is universal. It's called true solar time, and there's nothing specifically Korean about it. Our calculation applies it to any city. An example from the site's engine: for Moscow in summer 1990 the correction came to minus 94 minutes. About 90 of those come from the clocks: that summer Moscow ran on UTC+4, while its longitude of 37.6° E corresponds to roughly UTC+2:30. The remaining minutes are the seasonal correction of true solar time. The figure holds only for that place and season. Someone born in Moscow in summer 1990 at 01:30 by the documents arrived, by the Sun, at 23:56 the previous day: the Ox hour 丑 turned into the Rat hour 子. Under our engine's rule (the day changes at midnight), the Day Pillar changes too, while in a school that changes the day at 23:00 it stays the same. Why every minute matters is covered in Exact Time of Birth, and the manual recalculation in How to Calculate a BaZi Chart by Hand.

The Rat hour and the midnight debate

The span from 23:00 to 01:00 is the Rat hour (子時, zǐ shí). Korean schools argue about when to change the day: at 23:00 or at midnight. The debate has names: 야자시 (yajasi, 夜子時, the "night Rat hour") and 조자시 (jojasi, 朝子時, the "morning Rat hour"). Our calculation works like this: the day changes at midnight, and the hour stem for 23:00–00:00 is taken from the next day. This is called the late Rat hour. If you were born between 23:00 and 00:59, know that schools disagree here, and don't be surprised if another calculator shows a different Hour Pillar.

The year animal doesn't change at New Year

In everyday life, Koreans switch their year animal, 띠 (tti), at 설날 (Seollal), the lunar New Year. Saju, however, takes the boundary at 立春 (입춘, ipchun), around February 4. If you were born in January or the first days of February, check which of the two animals actually stands in your chart. We cover how this works with the 12 animals in a separate article.

5 Sal: the stars Koreans love

The most visible part of Korean pop culture around saju is 신살 (sinsal, 神殺), the symbolic stars Koreans call simply 살 (sal). People discuss them as eagerly as Westerners discuss zodiac sign compatibility. Here are the most common ones.

원진 (wonjin) is especially interesting. Its pairs are made from earthly branches: 子 and 未, 丑 and 午, 寅 and 酉, 卯 and 申, 辰 and 亥, 巳 and 戌. Two of the six pairs (子未 and 丑午) coincide with the classical "harm" 害 (hài), which we covered in the Six Harms. The other four don't match the harms, so 원진 can't be treated as just a Korean name for 害.

The classical Chinese school is cautious about stars in general. 《子平真詮》 (Zǐ Píng Zhēn Quán) has a separate chapter, "論星辰無關格局" ("On why the stars do not determine the structure of a chart"). Its point is easy to sum up: success and failure are decided by the structure set by the birth month and by the interplay of stems and branches, while stars are an add-on and shouldn't be relied on alone. So if you found a "white tiger" in your chart and got scared, put it back down: by the classics, a star doesn't determine the structure of the chart. The stars and their places in a chart are listed in the full 神煞 catalog.

6 The Day Pillar as character, and the Tojeong bigyeol mix-up

Another Korean feature is the huge body of 일주론 (iljuron) texts: descriptions of character by Day Pillar. There are sixty day pillars, and each gets a few paragraphs, often with ready-made labels. They're fun to read, but remember that in the Chinese school the Day Pillar is an important part of the chart, yet only one part. The structure of the month, the balance of elements and the current Luck Pillar can shift the picture noticeably. All sixty are covered in The 60 Day Pillars, and the role of the Day Master is explained here.

The other typical mix-up involves 토정비결 (Tojeong bigyeol, 土亭秘訣). It's a popular Korean New Year fortune that goes back to the 16th century and is based on the lunar date of birth. But it's a different system, not saju, even though the two are often confused. If you're offered a "saju for the year" with short predictions like "this year brings movement in your affairs," ask which system it was calculated by: it may be an annual saju reading, or it may be Tojeong bigyeol.

7 Why saju became fashionable in Korea

Interest in saju has grown noticeably among Koreans in their twenties and thirties. There are chart apps, "saju cafés" where your chart is explained over coffee, and TV shows and dramas where characters go to see a practitioner. Why exactly is anyone's guess: a chart gives people a ready-made language for talking about character and life choices, and a playful one at that, the kind you're not embarrassed to bring to friends.

This fashion has a practical side. Mass-market apps squeeze the calculation into a couple of screens and hand out bright labels based on the Day Pillar or a pair of sal. If a result looks odd, check two things first: whether the birth time was corrected for the place, and how the app handles the Rat hour. We covered both in section four.

8 What from the Korean set we calculate, and what we don't

The bazi.cards engine calculates four of the seven stars mentioned above: 桃花 (dohwa), 驛馬 (yeongma), 華蓋 (hwagae) and 紅艷 (hongyeom). It doesn't calculate the other three, 원진, 귀문관 and 백호: they belong more to Korean popular practice than to the classical Chinese 子平 (zǐ píng) school our readings are built on. If seeing those three stars matters to you, our reading won't show them, and it's better to know that up front.

What our readings give you otherwise depends on the depth. The free chart shows the Day Master, the four pillars and the balance of the five elements: in other words, the same saju, calculated for your place of birth. The Standard reading turns the chart into text according to the classical school: character, elements, the Ten Gods, resources, relationships. The Korean theme of 궁합 (gunghap, a couple's compatibility) is covered by a separate compatibility section, whose mechanics are described in the five layers of compatibility. And if you'd like to get the basics straight first, start with the beginner's guide.

If you already have an old Korean chart and it shows the Rat hour or a January date, compare it with ours: the difference will almost certainly come down to the time correction or the day boundary, while the characters themselves stay the same.

9 Frequently asked questions

Are saju and BaZi the same thing?

Yes, they're two language versions of one four-pillar system. 사주 is the Korean reading of the characters 四柱, and 사주팔자 is the Korean name for 四柱八字, the Chinese 八字. The same birth data gives the same eight characters in any country.

How do I calculate my saju from my date of birth online?

You need your date, time and city of birth. Any correct four-pillar calculator, including the free bazi.cards chart, will show the same characters; only the interpretation will differ. Enter the time with your place of birth in mind.

How does saju differ from BaZi in practice?

The math is the same; the habits differ. In Korea practitioners usually subtract about 30 minutes because of the gap between the time zone and Seoul's longitude, argue about the day boundary in the Rat hour, and love sal stars and detailed Day Pillar descriptions.

Is Tojeong bigyeol a kind of saju?

No. 토정비결 is a different Korean New Year fortune for the year ahead, which goes back to the 16th century and works from the lunar date. It's often confused with saju, but it's a separate system.

Do I need a lunar date for saju?

No. Korean sites ask for a lunar or solar date only as an input format. The pillars are built on the solar seasons either way, so your ordinary date of birth is what counts.