The short answer
Bazi and Korean Saju are the same calculation system read by two different traditions. Both take your birth date and time and convert them into four "pillars" (year, month, day, hour), and each pillar holds one Heavenly Stem and one Earthly Branch. That gives eight characters total, which is why the Chinese name is Bazi (八字, "eight characters") and the Korean name is Saju (사주, "four pillars" or 四柱). Feed the same birth data into a Bazi chart and a Saju chart and you get the same eight characters. The math does not change at the border.
What changes is the interpretation. Korea received the Four Pillars system from China centuries ago and then spent those centuries developing its own reading style. So if you have ever wondered whether a "Korean Saju reading" and a "Chinese Bazi reading" are secretly the same product with a different label, the honest answer is: same engine, different driver.
This guide breaks down exactly what is shared, what diverged, and which one you actually want depending on what you are looking for.
Same engine: the parts both systems share
Both Saju and Bazi are built on the same cosmological pieces:
- Five Elements (오행 / 五行): Wood, Fire, Earth, Metal, and Water, each in a Yin and a Yang form.
- Ten Heavenly Stems and Twelve Earthly Branches: the two cycles that combine to form the sexagenary cycle of sixty stem-branch pairs.
- Four-pillar structure: year, month, day, and hour, each a stem-branch pair.
- The Day Master: the Heavenly Stem of the day pillar, which represents you and acts as the reference point for reading everything else in the chart.
The chart-construction step (converting a Gregorian date and time into the traditional sexagenary calendar) is essentially identical in both. According to the Wikipedia entry on the Four Pillars of Destiny, the system "derives its name from its core structure: four 'pillars', each consisting of a pair of characters — one Heavenly Stem and one Earthly Branch — corresponding to the year, month, day, and hour of birth." That description applies word for word to Saju.
So the eight characters are not a regional variant. They are the shared foundation.
Different driver: where Korean Saju went its own way
The split started with transmission. The Four Pillars system reached the Korean peninsula and was absorbed during the Goryeo Dynasty (918–1392). It was not copied as a finished product. Korean scholars folded it into frameworks Korea already had, including indigenous and shamanic traditions, and adapted it to local social and political life.
A few practical differences that came out of that long divergence:
- Strong vs. weak Day Master. Modern Chinese Bazi leans heavily on a "Useful God" theory that asks whether the Day Master is strong or weak, then picks the element that balances the chart. Korean Saju practice is more split on this. A large share of Korean teaching downplays rigid strong/weak labels and reads the relationships between all eight characters instead.
- The Ten Gods lens. Korean Saju puts distinct interpretive weight on the Ten Gods structure to describe how the other characters relate to the Day Master.
- Auxiliary stars (Sinsal / 신살). Korean readings often layer in these auxiliary markers in a way that has its own Korean development.
- Cultural register. A Korean reading is delivered in the vocabulary and emphasis Korean practitioners built over centuries, which is why it can feel different even when the chart is identical.
None of this is a contradiction. It is the difference between two schools reading the same text.
Frequently asked questions
Is Saju just the Korean word for Bazi?
Not quite. "Saju" is the Korean name for the same four-pillar chart, but Korean Saju also refers to the specific Korean interpretive tradition that grew around that chart. The chart is shared; the reading tradition is Korea's own.
Will a Bazi calculator give me the right Saju chart?
The eight characters will match, because the calendar math is the same. What a Bazi calculator usually will not give you is the Korean-style interpretation, since most Bazi tools follow Chinese reading conventions. If you want the Korean reading, use a tool built for Saju.
Which one should I use?
If you are drawn to the Chinese school's strong/weak Day Master balancing and Useful God approach, Bazi tools fit better. If you want the relational, Ten-Gods-forward Korean style, look for a dedicated Saju reading. Either way, your eight characters are fixed by your birth data.
Do I need to know Chinese characters to read it?
No. Modern tools convert your birth date and time for you and present the chart in plain language. A Korean Saju reading at sajuapp.app is available in several languages and explains the pillars without requiring you to read Hanja.
How to actually try it
You do not need to hand-calculate the sexagenary calendar. Enter your birth date and time of birth (the hour matters, because it sets the hour pillar and affects the reading), and a tool generates the four pillars for you.
If you want the Korean interpretation specifically, you can get a free Korean Four Pillars reading at sajuapp.app, which builds the chart from your birth data and walks you through what each pillar represents.
The bottom line
Bazi and Saju are not rivals and they are not duplicates. They are the same Four Pillars system, the same eight characters, read through two traditions that have been developing separately for several hundred years. Pick the reading style that matches what you want to learn, and remember that the chart underneath is the same either way.
Sources: Four Pillars of Destiny — Wikipedia; Heavenly Stems — Wikipedia; Earthly Branches — Wikipedia.
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