Saju Basics: Four Pillars and the Five Elements

This is a fortune corner for fun. Unlike the other tests on Nadapge, it is not research-based and is separate from your analysis results.

What is saju?

Saju (四柱) means “four pillars.” Your birth year, month, day and hour each become one pillar, and each pillar is written with two characters: a heavenly stem on top and an earthly branch below. Four pillars times two characters gives eight characters, which is why Koreans call it saju palja, “four pillars, eight characters.”

The system grew out of ancient Chinese calendar science. Astronomers who tracked the Sun and Moon labeled years and days with a repeating set of 60 names, the sexagenary cycle (60 gapja). It runs gapja, eulchuk, byeongin and so on, and after the 60th name (gyehae) it starts over. The Korean 60th birthday, hwangap, literally means “the return of gapja.” In Korea this calendar has been part of everyday culture for centuries, from choosing wedding dates to naming children.

Ten stems and twelve branches

There are 10 heavenly stems and 12 earthly branches. Pairing them in order gives 60 combinations (the least common multiple of 10 and 12). Each character carries one of the five elements (wood, fire, earth, metal, water) and a yin or yang polarity.

Element	Stems (yang, yin)	Branches (main element)
Wood	Gap, Eul	In, Myo
Fire	Byeong, Jeong	Sa, O
Earth	Mu, Gi	Jin, Sul, Chuk, Mi
Metal	Gyeong, Sin	Sin, Yu
Water	Im, Gye	Ja, Hae

The branches run Ja, Chuk, In, Myo, Jin, Sa, O, Mi, Sin, Yu, Sul, Hae and line up with the twelve zodiac animals (Rat, Ox, Tiger, Rabbit and so on). Tradition says each branch hides several elements inside it, but Nadapge counts only each branch’s main element.

How the pillars are worked out

• Year pillar: changes at Ipchun, the “start of spring” solar term (around February 4), not on January 1 or Lunar New Year. If you were born in January or early February, your year pillar may belong to the previous year.
• Month pillar: changes at 12 of the 24 solar terms (Ipchun, Gyeongchip, Cheongmyeong, Ipha, Mangjong, Soseo, Ipchu, Baengno, Hallo, Ipdong, Daeseol, Sohan), not on the 1st of the month.
• Day pillar: a continuous 60-day cycle that never resets at the start of a month or year.
• Hour pillar: the day is split into twelve 2-hour blocks. The Ja hour is 23:00 ~ 01:00, Chuk is 01:00 ~ 03:00, In is 03:00 ~ 05:00, and so on through Hae (21:00 ~ 23:00).

Adjusting your birth time

Korea Standard Time is UTC+9, based on the 135°E meridian. Seoul sits near 127°E, so the Sun actually reaches its highest point about 30 minutes later than the clock suggests. By default, Nadapge subtracts 30 minutes from your birth time before working out the hour pillar.

More precisely, the correction is “Korea’s official UTC offset at the moment you were born, minus 8 hours 30 minutes.” Korea’s time history is taken from the international time zone database (IANA tz, Asia/Seoul), so the correction changes with it:

• Under normal UTC+9, 30 minutes are subtracted.
• From March 21, 1954 to August 9, 1961, when Korea used UTC+8:30, and for births before 1912, nothing is subtracted.
• During daylight saving periods (19481951, 19551960 and 1987~1988), one extra hour is subtracted.

If you’d rather not use this correction, you can turn it off.

If you don’t know your birth time, the hour pillar is simply left out and the reading uses the other three pillars. Lunar birthdays are converted to the solar calendar with a table based on KASI (Korea Astronomy and Space Science Institute) data, and leap months are handled correctly.

Element balance and the day master

Count the element of every stem and branch in your chart (eight characters, or six without the hour) and you get your element balance: which elements are plentiful and which are scarce.

The most important character is the day master, the stem of your day pillar. Saju treats it as “you,” and every other character is read in relation to it.

The ten gods: how other characters relate to you

The elements feed each other in a cycle (wood → fire → earth → metal → water → wood) and also control each other (wood controls earth, earth controls water, water controls fire, fire controls metal, metal controls wood). Combining that cycle with whether the polarity matches gives ten named relationships, called the ten gods.

Relation to your day master	Same polarity	Opposite polarity
Same element	Bigyeon (Friend)	Geopjae (Rival)
Element you produce	Siksin (Eating God)	Sanggwan (Hurting Officer)
Element you control	Pyeonjae (Indirect Wealth)	Jeongjae (Direct Wealth)
Element that controls you	Pyeongwan (Seven Killings)	Jeonggwan (Direct Officer)
Element that produces you	Pyeonin (Indirect Resource)	Jeongin (Direct Resource)

For example, if your day master is Gap (yang wood) and you meet Byeong (yang fire), that is “an element you produce, same polarity,” so it’s Siksin. The traditional names sound dramatic, but they are just labels for these relationships.

How Nadapge builds your reading

The yearly, monthly and weekly readings all follow the same steps.

1. Find the pillar for the period. The year uses the year pillar (switching at Ipchun) and the month uses the month pillar (switching at the solar term). For the week, which runs Monday to Sunday, we use the day pillar of Thursday, the midpoint of the week. It’s the same idea ISO week numbering uses when it assigns a week by its Thursday.
2. Look up which of the ten gods that pillar’s stem is for your day master. That sets the theme.
3. Check whether the period’s elements (its stem and branch) supply your weakest element, or pile more onto an element you already have plenty of.
4. Your lucky color and number come from that weakest element. Numbers follow the traditional pairing: water 1 and 6, fire 2 and 7, wood 3 and 8, metal 4 and 9, earth 5 and 10.

The star rating uses a simple, fixed formula. It starts at 3, adds 1 point each if the stem or branch supplies your weakest element, takes away 1 if the period feeds your strongest element when you already have three or more of it, then nudges by half a point depending on the ten god (up for Sik-sin, Jeong-jae, Jeong-gwan and Jeong-in; down for Geop-jae, Sang-gwan and Pyeon-gwan), and rounds to a whole number from 1 to 5. The same birth details and the same date always give the same result. Nothing is random.

Please keep in mind: there is no scientific evidence

There is no scientific evidence that saju can predict personality or future events. When astrology was put to a double-blind test (Carlson, 1985), astrologers did no better than chance at matching birth charts to people. Saju reads people from their moment of birth in much the same way, so it shares the same limits.

Enjoy saju as a long-standing piece of culture and a fun conversation starter. Saying “apparently I have a lot of wood” can be a nice way to open up a chat with friends. But please don’t base important decisions about school, work, money, health or relationships on it. Lean on real information and people you trust instead. If you want to understand yourself better, try the evidence-based tests on Nadapge too.