Synastry chart calculator
Enter two sets of birth data. The calculator computes every major aspect between Chart A's planets and Chart B's bodies, and places each chart's planets into the other chart's houses. All computation runs in your browser.
What this calculator does
Synastry is the classical comparison of two natal charts. The geometric relations — aspects between Chart A planets and Chart B bodies, and where each set of planets falls in the other's houses — are factual properties of the two birth moments.
Some astrological traditions interpret synastry as a relationship framework. This page presents the geometry only. See disclaimer for our framing.
See also birth chart, transit chart, solar return.
Reference, not advice
This is cultural and astronomical reference, not personal prediction or advice.
Synastry aspects are geometric relations between two birth charts. They are not a relationship recommendation, compatibility score, or prediction of any outcome.
Last reviewed .