Free Synastry Chart Calculator

Compare two birth charts to reveal cross-aspects, house overlays, and an AI-powered relationship compatibility score.

What is a Synastry Chart?

A synastry chart is an astrological compatibility technique that overlays two individual birth charts to measure how one person's planetary energies interact with another's. Unlike Sun-sign compatibility (which only compares two signs), synastry evaluates dozens of cross-aspects — the angular relationships between every planet in Chart A and every planet in Chart B.

The 5 Key Synastry Aspects

• Conjunction (0°): Planets merge energy — intense and amplifying.
• Trine (120°): Natural harmony and easy flow between the two energies.
• Sextile (60°): Supportive interaction with room for growth.
• Square (90°): Tension and friction that fuels development through challenge.
• Opposition (180°): Polarizing push-pull creating attraction and complementary balance.