Zodiac compatibility calculator
Traditional compatibility runs on elements rather than on signs directly. Same element is considered easiest, fire with air and earth with water are complementary, and fire with water is the classic friction pairing. That is the whole system — which means the score here is a lookup table with four possible values, not a measurement of anything. It is presented as what the tradition claims, nothing more.
This has no predictive value whatsoever. Relationships are not determined by birth dates, and no study has ever found otherwise. It reports what the tradition says.
Traditional compatibility is judged by element. Same element scores highest; fire with air and earth with water are considered complementary; fire with water is the traditional friction pairing. It is a lookup, not a measurement.
How the compatibility scheme works
Serious astrologers would consider sun-sign compatibility close to meaningless even within their own framework, because it ignores everything a full synastry reading uses — Moon and Venus placements, aspects between charts, house overlays. Reducing two people to one variable each and then to four possible scores is the astrological equivalent of judging a book by its page count. It is what the popular version does, so it is what this page reports.
Questions
Traditionally those sharing an element, then fire with air and earth with water.