Compatibility
Two birthdays, one little spark-check. Saju compatibility looks at your elements and signs — gently, never as a verdict.
What this screen reads, and what decides the answer
This screen reads 2 things and no more: one birth date from each of you. Not the hour of birth, not your sex, not your names, not a photo. From each date it builds two positions of the Four Pillars chart — the year pillar and the day pillar — and then asks the same short set of questions of both charts, layer by layer.
| Layer | What it reads in the chart | Answers it can give |
|---|---|---|
| Surface element | The element of the heavenly stem of the birth year | 3 |
| Zodiac sign | The earthly branch of the birth year | 4 |
| Day master | The element of the heavenly stem of the birth day | 3 |
The 3 layers are asked in the order they stand here, and inside each layer the possible answers are asked from the top down — the first one that matches wins, and the rest are never reached. Nothing else weighs in: not how long you have known each other, not who asked, not anything either of you typed beyond a date.
What comes out is one of 4 names and nothing else — a rare match, warm and well-matched, a bond worth tending, or opposites that teach. There is an internal tally behind those names, and it stays internal: no number, no percentage, no bar. That is a decision rather than an omission. A checkable number attached to another person's feelings invents a precision nobody has, and it trains a daily re-check. So the layers are published instead of the score, and you can read the reasoning rather than a verdict.
Nothing here is drawn at random. The same two dates always give the same name and the same three sentences, on any device and at any hour. Swapping who goes first does not change the name either, because every question a layer asks is symmetric — only the order the two signs appear in the sentence follows the order you typed.
Neither date leaves this device. The reading is worked out in your browser, so the other person's birthday is never sent to a server and nothing is kept once you close the page. And what the layers describe is two charts, not two people: nothing here says a bond should be kept or ended. That part was never the chart's to decide.
How the elements meet, and how the signs meet
The 5 elements stand in a circle. Each one feeds the next (生) and checks the one it skips over (剋). Those two cycles are the oldest machinery in Saju, and they are the whole of what the element layers ask. The table reads across: the element on the left feeds the middle column and checks the right one.
| Element | Feeds (生) | Checks (剋) |
|---|---|---|
| Wood | Fire | Earth |
| Fire | Earth | Metal |
| Earth | Metal | Water |
| Metal | Water | Wood |
| Water | Wood | Fire |
Between them the two cycles reach every pair, so two different elements are never simply neutral — one always feeds or checks the other, whichever way round they are read. Counting all 25 ordered pairs of the 5 elements: same element 5 · feeding 10 · checking 10 · neither 0.
| Harmonious group (三合) | Its branches | What each one faces (沖) |
|---|---|---|
| Rat·Dragon·Monkey | 子·辰·申 | Horse·Dog·Tiger |
| Ox·Snake·Rooster | 丑·巳·酉 | Goat·Pig·Rabbit |
| Tiger·Horse·Dog | 寅·午·戌 | Monkey·Rat·Dragon |
| Rabbit·Goat·Pig | 卯·未·亥 | Rooster·Ox·Snake |
A harmonious group is made of three different branches, so two people born under the same sign do not form one. That case gets an answer of its own — a shared rhythm rather than a triangle — because calling it a trine would put a name on it that the tradition does not. Counting all 144 ordered pairs of the 12 branches: same sign 12 · harmonious group 24 · facing pair 12 · none of those 96.
One thing worth knowing before reading your own row: the Saju year does not turn on New Year's Day. It turns at 입춘 (立春, the beginning of spring, in early February), and this screen computes that moment from the solar terms rather than assuming it. So a birthday in January, or in the first days of February, belongs to the year before the one on the certificate — and that earlier year is the sign this whole table is about.
What a layer says is how two charts sit against each other, not what will happen between two people. Nothing on this screen is medical, legal, or financial advice, and no row here measures anyone's worth.
How this compatibility reading is calculated
How two birth charts relate on three layers — surface element, zodiac-animal bond, and day-master element — collapsed into one symbolic harmony tier, never a number.
Each layer is scored internally by fixed rules (element generates/controls, zodiac trine/clash, day-master relation), summed, then mapped to one of four tiers — golden, warm, tending, or opposites. The internal tally never leaves the calculation; only the tier and its prose do.
We never show the internal number, and we never attach a checkable score to another person's feelings — that's D-003, our own hard boundary. This compares two birth charts, not either person's actual feelings or intentions.
How this compatibility reading is calculated
No — the internal tally never leaves the calculation. Only the four symbolic tiers (golden, warm, tending, opposites) and their prose reach the screen, by design (D-003).
No — it compares two birth charts (elements, zodiac, day masters), not psychology or intent. For a reading about how someone feels, see /heart instead.