Saju compatibility is what Korean families call gunghap (궁합, 宮合): two birth charts read side by side, traditionally consulted before marriage in Korea. Saju (사주, 四柱) is the Korean name for the Four Pillars, the same system this site calls Ba Zi (八字 bāzì), so the method below is the one we use for any couple. The saju overview covers what the two traditions share.
A real gunghap reading compares four things in order: the two Day Masters, the two day branches, the balance of elements across both charts, and the timing of each person’s luck pillars. None of these reduces to a single number, and that is deliberate.
Why the year-animal match is a blunt instrument
The popular version of compatibility looks only at the two birth-year animals: Rat with Ox, Tiger with Monkey, and so on. It uses one character out of eight from each chart, and it is the character that speaks least about a marriage. The year branch describes family background and the generation you were born into. Everyone born in the same Li Chun (立春 lìchūn) year shares it.
The classic mistake is to reject a match because the animals clash, when the day branches combine and the elements support each other. The reverse also happens: two animals that “get along” sit over day branches that punish each other. Animal pairings are a reasonable starting conversation. They are not a gunghap. If you want the folk version for interest, the zodiac compatibility pages set it out pair by pair.
Step one: the two Day Masters
The day stem, 일간 (ilgan, 日干) in saju vocabulary, is each person’s Day Master: how they meet the world. We read the two stems first as elements. Does one feed the other in the production cycle, does one control the other, or are they the same element standing side by side? A Water Day Master with a Wood partner tends to give; a Metal Day Master with a Wood partner tends to cut and shape.
Then we check whether the two day stems form a stem combination (天干合 tiāngān hé), a classical pairing in which the stems bind. A combination between day stems is read as natural attraction and ease of understanding. It is a good sign, not a promise of a good marriage, because the rest of both charts still has a say. The Day Master guide explains each stem’s temperament in more depth.
Step two: the spouse palace
The day branch is the spouse palace (夫妻宫 fūqī gōng). It sits directly under the Day Master and shows what each person brings into a partnership and how they live inside one. In saju compatibility this is where most of the weight falls. We check the two day branches against the fixed lists of branch relations:
| Relation | Pairs | How it reads between day branches |
|---|---|---|
| Six Combinations (六合 liùhé) | 子+丑→Earth, 寅+亥→Wood, 卯+戌→Fire, 辰+酉→Metal, 巳+申→Water, 午+未→Fire/Earth | Binding influence; the two palaces pull together |
| Three Harmonies (三合 sānhé) | 申子辰→Water frame, 寅午戌→Fire frame, 巳酉丑→Metal frame, 亥卯未→Wood frame | Two members of the same frame share a direction |
| Six Clashes (六冲 liùchōng) | 子↔午, 丑↔未, 寅↔申, 卯↔酉, 辰↔戌, 巳↔亥 | Instability signal; movement, friction, distance |
| Six Harms (六害 liùhài) | 子↔未, 丑↔午, 寅↔巳, 卯↔辰, 申↔亥, 酉↔戌 | Quiet friction; small grievances that accumulate |
| Punishment (刑 xíng) | 子–卯, 丑–未, 丑–戌, 寅–巳, 寅–申, 巳–申, 未–戌 | Complication under stress; fine in calm seasons, sharp in hard ones |
Some pairs carry more than one relation. 寅 and 申 clash and punish; 巳 and 申 combine and punish; 寅 and 巳 harm and punish; 丑 and 未 clash and punish. These need careful reading, and the guide to the punishments explains how. For the branch-by-branch detail, see day branch compatibility.
We also look at the spouse star in each chart. For a man, Direct Wealth (正财 zhèngcái) is classically the wife star; for a woman, Direct Officer (正官 zhèngguān) is the husband star. Where that star sits, and whether it is clashed or combined, colours what each person expects from a partner.
Step three: element balance across both charts
Every chart leans toward some of the five elements, 오행 (ohaeng, 五行), and away from others. Each person has a useful element, 용신 (yongsin, 用神), the element that brings their chart into better balance. The most practical question in gunghap is simple: does one chart supply what the other lacks?
If her chart is heavy with Fire and needs Water, and his chart is rich in Water, she will often feel steadied by him. If both charts are short of the same element, the relationship can feel warm but under-resourced, with both people looking outward for the same thing. This is where two charts that look ordinary on the surface can turn out to fit well. Judging a useful element correctly depends on Day Master strength, covered in strong vs weak Day Master.
Step four: luck-pillar timing
Natal charts describe the people. Luck pillars, 대운 (daeun, 大運), describe the decade each person is living through. Two compatible charts can still meet at a difficult time: one person in a decade of expansion and travel, the other in a decade that asks for rest and consolidation. A clash to the day branch arriving in one person’s luck pillar is a season to talk more, not a reason to end anything.
We read the next ten to twenty years for both people together. Timing explains a great deal of what couples experience as “we used to be so easy together”. The concept is laid out in luck pillars (Da Yun).
What a saju compatibility reading gives you
It gives you a map of where two people support each other, where friction is built in, and which years will test the arrangement. It does not give a percentage. Any “87% match” score has thrown away exactly the detail that makes the reading useful. Charts are maps, not verdicts, and a couple who understand their friction points usually handle them well.
To see the four layers for your own pair, cast both charts with the compatibility tool, then read the wider method in Ba Zi marriage compatibility.
For a full gunghap, book one of our readings: one hour, both charts on the table, a written summary afterwards, and no fear-selling.