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Synastry chart calculator
Compare two birth charts to see how your planets interact — the astrological way of looking at compatibility.
Frequently asked questions
What is a synastry chart?
Synastry compares two birth charts by measuring the angles (aspects) between one person's planets and the other's. Astrologers use it to describe the dynamics of a relationship.
Which synastry aspects matter most?
Astrologers usually look first at Sun–Moon, Venus–Mars, Moon–Moon and Saturn contacts, and at aspects to the Ascendant when both birth times are known.
Do both people need birth times?
No. Planet aspects work from birth dates and places; birth times add the Ascendant and make the Moon exact.
Astrology is a symbolic and cultural tradition. The planetary positions on this site are calculated with astronomical accuracy; the interpretations describe what astrologers associate with them and are not scientifically validated predictions about personality, relationships or the future.