Every culture that watched the stars eventually pointed them at two people in love and asked: does this work? Are these two actually meant for each other? Western astrology answers with synastry. Korean tradition answers with 궁합 (gunghap). Different tools, same anxiety.
Synastry overlays two birth charts and checks the angles. Your Venus trines their Mars? Chemistry. Your Saturn squares their Moon? Emotional friction, probably. It also builds a composite chart, a third chart representing the relationship itself, and reads that like a natal chart. Strengths, challenges, the whole thing.
궁합 takes a different structural route. No planetary angles. Instead, it compares the five-element balance of two Saju charts. Each person has a dominant element plus a set of supporting or conflicting ones. A good match means the two profiles fill each other's gaps. One person's excess is the other's deficit. Natural balance. A bad match means the same elements collide. Two Fire-dominant charts might generate heat, sure, but also a lot of smoke.
The Day Master comparison sits at the center of 궁합, the way Sun-Moon-Venus sits at the center of Western synastry. Your Day Master is your core self in Saju. Readers check whether two Day Masters generate each other in the five-element cycle or control each other. Wood feeds Fire, so a Wood Day Master with a Fire Day Master reads as naturally harmonious. Metal chops Wood? More complicated.
Timing matters in both systems too. Synastry checks transits, how current planetary movements activate the composite chart. 궁합 checks 대운 (daewun), ten-year luck cycles, to see whether two people's fortune trajectories run parallel or diverge. A couple peaking at the same time? Well-matched. Alternating decades? Mismatched rhythms, potentially.
The cultural weight differs, though. In the West, synastry is mostly a self-understanding tool. Couples read their composite chart for insight, but nobody's calling off a wedding over a tough Saturn aspect. In Korea, 궁합 historically carried more gravity. Families exchanged 사주 (birth data) before arranging marriages. A bad reading could genuinely kill a match. That's softened a lot, but 궁합 is still a common dinner-table topic for Korean couples.
What both traditions land on, underneath all the machinery: compatibility isn't similarity. Two identical charts wouldn't necessarily make a good couple. The best matches involve complementarity. Different strengths filling different gaps. A dynamic whole instead of an echo.
Neither system is science. Both encode centuries of humans watching other humans love each other and trying to find the pattern. Reading your compatibility through both lenses is less about getting an answer and more about thinking about your relationship from two angles you'd never pick yourself.
The Compatibility tool here calculates both partners' Saju charts and generates a 궁합 reading. Free to try. If you've also got a Western synastry chart lying around, comparing the two is genuinely interesting.