What is saju?
Saju (사주, pronounced “sah-joo”) is Korean astrology based on the moment you were born. It turns your birth year, month, day and hour into eight characters, then reads how the five elements inside them push and pull on each other. Koreans use it the way some people use a personality test: to make sense of themselves, their relationships and the timing of big decisions. Here’s how it actually works, without the jargon.
Where the name comes from
Saju literally means “four pillars.” The idea is that your life rests on four supports, one for each unit of time at your birth: year, month, day and hour. Each pillar holds two characters, so a full chart has eight. In Korean you’ll also hear it called saju palja, “four pillars, eight characters.”
The system came from China, where it’s called bazi, and has been part of Korean life for centuries. Today you’ll find saju cafés in Seoul, saju apps with millions of users, and grandparents who still check a couple’s charts before a wedding. Most people don’t treat it as fate. They treat it as a conversation starter about who they are, the same way friends compare personality test results over drinks.
The four pillars and the eight characters
Each pillar has a top character and a bottom one. The top character is called a heavenly stem. There are ten of them, and each is an element with a yin or yang side: Yang Wood, Yin Wood, Yang Fire, and so on. The bottom character is an earthly branch. There are twelve, and you already know them as the zodiac animals: Rat, Ox, Tiger and the rest.
So your year pillar might be Fire over Horse, your month Earth over Ox, and so on. Your birth-year animal, the one on restaurant placemats, is only one of the eight. That’s the first surprise for most people: in saju, the year is not the main event.
The year pillar is usually read as your roots and the world you grew up in. The month pillar describes your working life and the season you were born into, which sets the temperature of the whole chart. The day pillar is you and your closest relationships. The hour pillar covers your inner life and later years.
Your day master: the part that’s you
The top character of your day pillar is called your day master (일간, ilgan). Saju treats it as the self. Every other character in the chart is read by how it treats your day master: does it feed you, drain you, test you, or keep you company?
There are ten day masters, one for each stem. On this site we give each one an image so it’s easy to remember: the Tree, the Flower, the Sun, the Candle, the Mountain, the Field, the Sword, the Jewel, the Ocean and the Rain. A Yang Wood person (the Tree) and a Yin Water person (the Rain) can be born in the same year and still read as completely different people.
Pair your day master with the animal underneath it and you get your saju type, like the Candle Rabbit or the Mountain Dog. There are sixty of these, and they repeat every sixty days.
The five elements and how they push each other
Everything in saju belongs to one of five elements: Wood, Fire, Earth, Metal and Water. They aren’t really substances. Think of them as five kinds of energy. Wood grows, Fire spreads, Earth holds, Metal cuts, Water flows.
The elements relate in two loops. In the feeding loop, each one helps the next: Wood fuels Fire, Fire leaves ash that becomes Earth, Earth holds Metal ore, Metal gathers Water like dew on a cold blade, and Water feeds Wood. In the shaping loop, each one keeps another in check: Wood breaks up Earth, Earth dams Water, Water puts out Fire, Fire melts Metal, Metal cuts Wood.
A reader counts how much of each element is in your chart and where it sits. Too much of one and you tend to overdo its traits. A missing one often shows up as a skill that takes you extra effort. Neither is a verdict. It’s a description of where your energy pools and where it runs thin.
Ten-year chapters and yearly luck
Your birth chart stays the same all your life, but saju also tracks time moving past it. Your life is split into chapters of about ten years, called daeun (대운). Each chapter brings its own stem and branch, so each decade adds a different element to the mix. A Tree who spends their twenties in a Water chapter might feel supported and studious, then find their thirties louder and more public in a Fire chapter.
On top of that, every calendar year has its own pair of characters. 2027, for example, is a Fire Goat year. People in Korea check how the new year meets their chart around the Lunar New Year, half seriously and half for fun, the way you might read a horoscope on New Year’s Day.
Saju vs bazi
If you’ve seen the word bazi, you’ve seen saju. Bazi (八字) is the Chinese name and means “eight characters.” Saju (四柱) is the Korean name and means “four pillars.” The calendar math, the stems and branches, and the element rules are the same, so a saju calculator and a bazi calculator should give you the same chart.
The difference is in the reading. Korean saju culture leans hard on the day pillar and on relationships: who you’ll get along with, when to marry, how two people’s charts fit. It’s also casual and everyday in Korea, closer to checking your MBTI with friends than consulting an oracle.
Saju vs Western astrology
Western astrology maps the planets in the sky at your birth. Saju doesn’t use the sky at all. It works from the calendar, specifically from a cycle of sixty stem and branch pairs that counts years, months, days and hours. No planets, no houses, no telescopes.
The closest match to your sun sign is your day master, but the comparison only goes so far. Your sun sign is shared with everyone born in the same month. Your day master changes every day, so even siblings born a year apart almost never share one.
You don’t have to pick a side. Plenty of people know their sun sign and their day master and find that each one catches something the other misses.
How to read your own chart
Start with your day master. Read what it says about you and see what fits. Then look at your element balance: which element shows up most, and which one is missing. That pair of facts covers most of what a first reading tells you.
After that, check your compatibility with the people around you, and look at which ten-year chapter you’re in now. Saju is for fun and for thinking about yourself. It’s not a substitute for medical, legal or financial advice, and it can’t tell you what will happen. It can give you a new way to describe what already is. A good test: read your day master page, then send it to a friend who knows you well and ask what they think. Their reaction is often the most interesting part.