Korean saju compatibility is called 궁합 (gunghap). Grandmothers have checked it before weddings for generations, and today half of Seoul checks it before a second date. A traditional gunghap compares two entire charts and can take a professional reader an hour. Our compatibility pages do something smaller and, we think, more honest: they compare two Day Masters, the single character in each chart that stands for the person. Here is exactly how that works, what it is good for, and what it leaves out.
Step one: your two Day Masters
Your Day Master is the heavenly stem of the day you were born. There are ten, from Gap Wood, the tall pine, to Gye Water, the rain. Each one is an element (Wood, Fire, Earth, Metal or Water) with a polarity (yang or yin). Put two people together and there are 55 possible Day Master pairs, which is why we have 55 compatibility pages. Gap with Gi and Gi with Gap are the same page, because the pairing is the same pairing, just read from the other side.
Step two: how the two elements relate
Every pair falls into one of three families. Same element: you are peers, two trees or two flames, with instant understanding and a built-in risk of competing. One feeds the other: Wood feeds Fire, Fire feeds Earth, Earth feeds Metal, Metal feeds Water, Water feeds Wood. These pairs tend to feel supportive and easy, though the one doing the feeding can get tired. One controls the other: Wood breaks up Earth, Earth dams Water, Water puts out Fire, Fire melts Metal, Metal cuts Wood. Control sounds harsh, but it is also how things get shape, so these pairs bring chemistry along with a question about power that is worth talking through.
Step three: polarity changes the feel
Two people with the same element relation can still feel very different, depending on whether their polarities match. In the Ten Gods (십신), a controlling element of the opposite polarity is Direct Officer or Direct Wealth, classically the partner stars, read as respectful, structured attraction. The same relation with matching polarity is Seven Killings or Indirect Wealth, which tends to feel more intense, competitive or adventurous. That is why Gap with Sin and Gap with Gyeong get different write-ups even though Metal cuts Wood in both.
Step four: combinations and clashes
Five stem pairs are famous for attraction. They are the heavenly combinations (천간합): 甲己 Gap and Gi, 乙庚 Eul and Gyeong, 丙辛 Byeong and Sin, 丁壬 Jeong and Im, 戊癸 Mu and Gye. Each joins a yang stem with the yin stem it controls, and they are read as natural magnetism, the classic "we just clicked". Four pairs are famous for friction. They are the heavenly stem clashes (천간충): 甲庚 Gap and Gyeong, 乙辛 Eul and Sin, 丙壬 Byeong and Im, 丁癸 Jeong and Gye. A clash means two strong currents meeting head on: honesty, spark and more arguments than average. It is a pattern to understand, not a sign that anything is doomed.
What the score means
Each pair page carries a number. It summarizes how those two Day Masters tend to interact: combinations rank highest, generating pairs come next, peers and partner-star pairs land in the middle, and same-polarity control pairs and clashes sit lowest. The score is symmetric, so it is the same whichever of you types first, and it is the same number the birthday check on the home page and the readings show. A lower number means more friction to work with, never "do not date this person". Many happy couples are clashes on paper and many easy matches drift apart.
What we deliberately leave out
A full Korean gunghap reads much more than Day Masters, and we would rather say so than pretend. When you enter two birthdays, we add one separate note about your day branches, the 일지 or spouse palace, which many Korean readers weigh as heavily as the Day Masters: whether they combine, clash or sit neutral. That note sits next to the score and never changes it. We skip punishments and harms between your spouse palaces, and we do not check 원진 (怨嗔), the six resentment pairs such as Rat and Goat or Tiger and Rooster, which Korean apps love. We also leave out hour pillars, the ten-year luck cycles (대운) that traditional readers use for timing, the useful-element (용신) match between two charts, and the gendered spouse stars of classical saju, because we read compatibility the same way for every couple.
Why we keep it this way
Day Masters are the part of saju that works best as a shared language. You can say "I'm a Byeong, she's an Im" the way friends say "I'm an ENFP, he's an ISTJ", and the pair page gives you something true and specific to talk about. The rest of the chart matters, and our longer readings use more of it. But no reading, however detailed, can tell you whether a relationship will last. That part depends on two people choosing each other, apologizing well and doing the dishes.
How to use a pair page
Read your own side first: what you need, how you text, where you clash. Then read theirs, ideally out loud, ideally together. The best compatibility conversation is not "are we a good match?" but "is this true for us, and what do we want to do about it?" Bom will tell you what is lovely about the pairing. Yeon will tell you what to watch. Both are trying to help.
The six families at a glance
| Family | Examples | Feels like |
|---|---|---|
| Heavenly combination | 甲己 Gap and Gi, 乙庚 Eul and Gyeong, 丙辛 Byeong and Sin, 丁壬 Jeong and Im, 戊癸 Mu and Gye | Natural magnetism |
| Generating (one feeds the other) | Wood and Fire, Water and Wood, Metal and Water | Supportive, easy, watch for one-sided giving |
| Same element (peers) | Gap and Eul, Byeong and Byeong | Instant understanding, risk of competing |
| Partner-star control (opposite polarity) | Gap and Sin, Byeong and Gye, Mu and Eul | Respectful, structured attraction |
| Same-polarity control | Gap and Mu, Byeong and Gyeong, Mu and Im | Intense, power questions |
| Heavenly stem clash | 甲庚 Gap and Gyeong, 乙辛 Eul and Sin, 丙壬 Byeong and Im, 丁癸 Jeong and Gye | Spark and friction, honest arguments |
FAQ
Is our compatibility score a prediction?
No. It describes how two Day Masters tend to interact. It cannot tell you whether a relationship will work, and no honest reading can.
Will my birthday check show the same score as the pair page?
Yes. The number comes from your two Day Masters, so the crush check, the pair page and the readings all show the same score, whichever of you goes first. With both birthdays we add a separate note on your day branches, which adds context but never changes the number.
What is the spouse palace, and where does it show up?
It is the branch under your Day Master, the 일지, which classical saju reads as your closest relationship space. Comparing two spouse palaces needs both birth dates, so a general pair page can't show it. Enter two birthdays in the crush check or the Situationship reading and we note whether your day branches combine, clash or sit neutral, separately from the score.
What is 원진?
Six branch pairs traditionally linked to mutual irritation: Rat and Goat, Ox and Horse, Tiger and Rooster, Rabbit and Monkey, Dragon and Pig, Snake and Dog. Korean apps check it often. Our pair pages leave it out, and we would not lose sleep over it either way.
Does gender change compatibility in saju?
In classical saju it changes which Ten God counts as the spouse star and the direction of luck cycles. We read compatibility the same way for every couple and say so up front.