"Chinese zodiac compatibility," in its narrowest sourced form, is the classification of a pair of animals as either a traditional San He trine member, a direct Liu Chong opposition, or unclassified by these two rules — never as a percentage, a verdict, or a prediction of relationship success.
The Chinese zodiac assigns one of twelve animals to each year in a repeating twelve-year cycle. When two people want to know how their animal signs relate, traditional materials list specific pair relationships rather than a single universal percentage. The most widely cited pair relationships come from two named frameworks: the San He (三合), often translated "Three Harmonies," which groups three animals into shared trines, and the Liu Chong (六沖), often translated "Six Clashes" or "Six Oppositions," which pairs six animals one-to-one across the cycle. A compatibility lookup built only on these two rules reports whether a given pair sits inside one named trine, sits across one named opposition, or falls outside both rule sets. That binary-and-residual structure is the literal meaning of the term in this limited browser; broader traditions add other layers, but those layers are not folded into the two-rule model.
What "compatibility" means inside this two-rule browser
In the context of this tool, compatibility is a very specific idea: it means "this pair is recognized by one of two sourced cultural rules." It does not mean "this pair is good for a relationship," "this pair is safe," or "this pair is recommended." The page labels a pair that sits in the same named trine as a traditional trine match, a pair that sits across a named opposition as a direct opposition, and every other pair of distinct animals as not classified by this limited two-rule model. The interface displays each animal's complete trine group and direct opposite so the classification can be verified from the source data rather than trusted as an unexplained badge.
The model is also intentionally symmetric. If Rat and Horse is reported as a direct opposition, Horse and Rat produces the same label. The browser offers a Swap control so the symmetry can be confirmed without retyping either selection. Symmetry matters because sourced cultural lists do not always rank pairs one-to-one; this tool restricts itself to the pairs that genuinely are reciprocal across the cycle, so the answer is the same however the two animals are entered.
The four San He trines
The Three Harmonies framework groups the twelve animals into four three-member trines. Each trine is treated as a shared-harmony set: any two distinct members of the same trine are labelled a traditional trine match. The four groups, taken as literal reference data, look like this:
| Trine | Members |
|---|---|
| 1 | Rat, Dragon, Monkey |
| 2 | Ox, Snake, Rooster |
| 3 | Tiger, Horse, Dog |
| 4 | Rabbit, Goat, Pig |
Across the four groups there are exactly twelve unordered trine pairs: three pairs within each three-member set, multiplied across the four groups. A sign paired with itself is not treated as a two-sign trine pair, so Rat with Rat does not register as a trine match. The trine labels follow the canonical cycle order Rat, Ox, Tiger, Rabbit, Dragon, Snake, Horse, Goat, Monkey, Rooster, Dog, Pig, which matches the order already used by the related Chinese Zodiac Calculator.
The six Liu Chong oppositions
The Six Clashes framework pairs six animals one-to-one across the cycle. Each animal in the cycle has exactly one opposite in this narrow model, and the six pairs never overlap the trine pairs above. They are read directly from cultural sources such as the Hong Kong Observatory's 12-year animal cycle reference and the zodiac harmony notes published by the National Folk Museum of Korea. The six pairs are:
| Opposition | Pair |
|---|---|
| 1 | Rat – Horse |
| 2 | Ox – Goat |
| 3 | Tiger – Monkey |
| 4 | Rabbit – Rooster |
| 5 | Dragon – Dog |
| 6 | Snake – Pig |
Working from the underlying arithmetic, C(12, 2) = 66 unordered pairs of distinct animals exist in the cycle. Of those, 12 sit inside a San He trine and 6 sit inside a Liu Chong opposition, leaving 66 − 12 − 6 = 48 pairs that sit outside both rules. Those residual pairs are listed openly in the companion guide on Chinese zodiac compatibility for the 48 unclassified pairs, so the residual set is not hidden or rounded away.
How to check what a pair means in the browser
A direct way to read what a particular pair means within this two-rule model is to use the Chinese Zodiac Compatibility browser. The steps below cover the only inputs the tool accepts and the only outputs it produces.
- Open the Chinese Zodiac Compatibility page in any modern browser; no sign-in, account, or download is required.
- Pick the first animal from the first selector using the canonical labels Rat, Ox, Tiger, Rabbit, Dragon, Snake, Horse, Goat, Monkey, Rooster, Dog, or Pig.
- Pick the second animal from the second selector; you do not need a birth year, and the tool does not convert Gregorian dates.
- Read the result line. It will read "Traditional trine (San He)," "Direct opposition (Liu Chong)," or "Not classified by this limited two-rule model."
- Inspect each animal's full trine group and direct opposite in the profile panels so the result can be confirmed from the displayed data, not an unexplained badge.
- Use the Swap control to flip the two animals and confirm the result is the same; this is the built-in symmetry check.
The browser performs no date or year conversion. Both selections stay in the page's React state and are not saved, uploaded, cached, or shared with any service. No name, birth date, gender, location, or relationship history is requested, so reading a pair leaves no personal trail inside the tool.
What the tool deliberately does not do
The two-rule browser is narrow on purpose. It does not turn a folk classification into a percentage, it does not rank people, and it does not predict whether a friendship, a family relationship, or a partnership will succeed. It does not silently treat Cat, Boar, Mouse, Cow, Sheep, or Ram as equivalents of Rat, Ox, or Goat; canonical interface labels and source aliases are kept separate, and regional variants that have not been declared in scope simply do not match. The tool also does not infer an animal from a Gregorian year, so the Lunar New Year boundary never enters the calculation — for year-to-animal lookup, the related Chinese Zodiac Calculator serves a different task and warns about that boundary directly.
Outside the two rules, "not classified" is not a verdict. The phrasing is chosen to make clear that the model says nothing about neutral, compatible, incompatible, safe, ideal, or doomed relationships. Cultural materials also document other branch relationships — Six Harmonies, harms, punishments, Five Element cycles — and a fuller BaZi or Four Pillars analysis that considers year, month, day, and hour branches together with element weights. None of those frameworks are merged into this browser, because merging them into one false universal table would hide the difference between a sourced two-rule lookup and a broader branch analysis.
Beyond the two rules
If a pair falls outside both the San He and Liu Chong sets, a reader interested in a fuller reading has several next steps. The simpler option is to leave it at the two-rule result and treat the absence as a literal absence, not as a judgment — the meaning of an unclassified pair in this model is simply that the pair is not in either sourced rule. A more involved option is to consult a practitioner who works within BaZi, also called the Four Pillars, because that system uses the four animal branches associated with year, month, day, and hour along with element relationships to produce a complete natal picture rather than a single pair label. A third option is to compare the two animals element by element, since each animal is associated with a traditional element — Rat and Monkey with water, Ox, Snake, and Rooster with metal, Tiger and Horse with fire, Rabbit, Goat, and Pig with wood, and Dragon and Dog with earth — and to use that element overlap as additional reading material rather than a definitive score.
For readers who simply want a transparent answer from the two sourced rules, the browser is the quickest way to read a pair without guessing the animal from a date. The displayed trine and opposition panels let a user verify the classification by eye, and the Swap control proves symmetry in one click, so the user is never asked to take an unexplained compatibility badge on trust.
If you're weighing options, Simplify I Ching Hexagram Meanings With Faster Lookups covers this in detail.