What is saju?

Four pillars, eight characters

Saju (사주) means "four pillars". It is an old Korean way of reading the moment someone was born. The year, the month, the day and the hour of birth each become one pillar, and each pillar is written with two characters: one on top, one below. Four pillars of two characters make eight, which is why Koreans often say saju palja (사주팔자), "four pillars, eight characters".

The idea came to Korea from China centuries ago and grew its own habits here. Today you hear the word in everyday talk ("it must be in my saju") as often as in a reading room. Plenty of Koreans have had their chart read at some point, usually with a smile and a pinch of salt.

Saju follows the solar year, not the calendar on the wall. A new saju year begins around February 4, at ipchun (입춘, "spring begins"), and each month pillar turns at one of the solar terms (jeolgi, 절기) rather than on the first of the month. The hour is read in sun time for the place of birth, so the same clock time in Toronto and in Sydney can fall in different hours.

Heavenly stems and earthly branches

The top character of each pillar is a heavenly stem (cheongan, 천간). There are ten of them, from Gap (甲) to Gye (癸). Each stem is one of the five elements in a firmer or a softer form: Gap is wood as a tall tree, Eul (乙) is wood as a climbing vine, Byeong (丙) is fire as the summer sun, Jeong (丁) is fire as a lantern, and so on.

The bottom character is an earthly branch (jiji, 지지). There are twelve, and they are the same twelve animals as the Chinese zodiac: Rat, Ox, Tiger, Rabbit, Dragon, Snake, Horse, Goat, Monkey, Rooster, Dog and Pig. The branch of the year pillar is the animal people mean when they say "I was born in the Year of the Dragon".

Stems and branches pair up in a cycle of sixty, and that cycle counts years, months, days and hours alike. Turning sixty is a big birthday in Korea for this reason: hwangap (환갑) is the year your birth pillar comes around again.

The five elements

Every one of the eight characters belongs to one of five elements (ohaeng, 오행): wood, fire, earth, metal and water. A reading starts by counting them. Some charts have plenty of one element and none of another; most sit somewhere in between.

The elements relate to each other in two simple circles:

• Feeding. Wood feeds fire, fire leaves earth (ash), earth holds metal, metal gathers water, water feeds wood.
• Shaping. Wood parts earth, earth banks water, water calms fire, fire softens metal, metal trims wood.

Neither circle is good or bad. A reader looks at the balance: where a chart has energy to spare, where it may run short, and what tends to help it settle. Think of it as a weather report for a temperament, not a grade.

The day master: the "you" of the chart

Of the eight characters, one matters most: the heavenly stem of the day pillar, called the day master (ilgan, 일간). Saju reads everything else in the chart in relation to it, the way you would describe a family by starting with one person in it.

Raonlog gives each of the ten day masters a picture, so the idea is easy to hold: a tall tree, a climbing vine, the summer sun, a lantern, a mountain, garden soil, raw iron, a polished gem, a wide river and spring rain. Our sample child Mina is an Eul wood day master, "the climbing vine": someone who may watch before she leaps and grows by finding her people.

How saju differs from Western astrology

People often ask if saju is "Korean astrology". They share a starting point, the moment of birth, but they work differently:

• Calendar, not sky. Astrology places the sun, moon and planets in the sky at your birth. Saju reads the calendar cycle of stems and branches; no planets are involved.
• The day matters most. A sun sign comes from the month, so everyone born in the same few weeks shares it. Your saju centers on the day you were born, so siblings born a few days apart can read quite differently.
• Balance, not a sign. Rather than placing you in one of twelve boxes, saju looks at how five elements mix across eight characters.
• Time unfolds in seasons. Saju also reads ten-year periods (daeun, 대운) and the year and month you are in, which is why Koreans like a reading at New Year.

Saju in Korean family life

In Korea, saju shows up at family moments more than at fortune tellers. When a baby is born, grandparents sometimes ask a name maker (jakmyeong, 작명) to suggest names whose characters add an element the chart has little of: a name with a water character for a chart short on water, for example. Before a wedding, some families compare the couple's charts (gunghap, 궁합), mostly as a talking point.

Around Lunar New Year, friends and coworkers swap their sinnyeon unse (신년운세), a light reading of the year ahead, the way others read a horoscope column. On a first birthday, the doljabi (돌잡이) game, where the baby picks one object from a table, is enjoyed in the same spirit: a story the family tells, not a plan for the child.

That is the spirit Raonlog Saju is written in: the chart as a way to talk about the people you love with curiosity. Why one child warms up slowly, what another needs after a busy day, how two people can be so different under one roof.

What Raonlog Saju does, and what it doesn't

Raonlog Saju works out the chart from the birth date, time and city (with sun time and daylight saving taken into account) and shows it free. For a fuller reading, Hak the crane writes seven short chapters for a parent: who the person is, what recharges them, how they learn and get along, the season they are in, and an answer to your own question.

• It does explain every point with the characters it comes from ("Why we say this"), so you can see the reasoning.
• It does suggest small, everyday things to try, like a line to say at bedtime.
• It doesn't predict events, judge ability or talk about health. It is a cultural reading for reflection: not a prediction, a diagnosis or professional advice.
• It doesn't keep your details for long. The reading and birth details are deleted after three months, or right away when you ask.

Saju schools read some details differently, and readings are written with AI from a checked chart. Take what rings true and leave the rest. Readings are free while we're starting out, for Raonlog letter subscribers. Curious? See a sample reading for Mina, a fictional child, or start a free reading.