Synastry Calculator

A synastry chart compares two birth charts by overlaying one person's planetary positions onto the other's chart. It analyzes the angular relationships (aspects) between planets in both charts to reveal areas of harmony, tension, attraction, and growth potential in the relationship. Key factors include Sun-Moon connections for emotional compatibility, Venus-Mars aspects for romantic chemistry, and Saturn contacts for long-term stability.

Our synastry calculator uses professional-grade astronomical algorithms for precise planetary positions, the same level of accuracy trusted by professional astrologers worldwide. The calculations account for your exact birth time, date, and location to compute accurate planetary longitudes, house placements, and inter-chart aspects with proper orb tolerances. For best accuracy, use your exact birth time from your birth certificate.

You need the birth date, birth time, and birth location for both people. The birth time is important because it determines the Moon sign (which changes signs every 2.5 days) and the Ascendant. If you don't know your exact birth time, you can use 12:00 PM (noon) as an approximation, though Moon and Ascendant positions may be less accurate.

Synastry compares two separate birth charts to see how the individuals interact with each other — it shows the chemistry and dynamics between two people. A composite chart creates a single chart by finding the midpoints of each planet pair, representing the relationship itself as its own entity. Our calculator provides both synastry aspects and a composite chart overview for a complete picture.

The most important aspects for romance include: Venus conjunct or trine Mars (strong physical and romantic attraction), Sun conjunct Moon (deep understanding), Venus conjunct Venus (shared values and love language), Moon trine Moon (emotional harmony), and Jupiter conjunct Venus (joy and abundance in love). Challenging aspects like Venus square Mars can also indicate intense passion.

Synastry reveals the dynamics and potential of a relationship, including areas that support long-term partnership. Key indicators for marriage include strong Saturn aspects (commitment), supportive Moon connections (emotional security), and harmonious Venus contacts (shared values). However, astrology shows potential — the success of any relationship depends on the choices and effort both partners put in.

Our compatibility score is a weighted calculation that considers multiple planetary connections including Sun, Moon, Mercury, Venus, Mars, Jupiter, and Saturn aspects between both charts. Scores above 75% indicate strong natural compatibility. Scores between 55-75% suggest good compatibility with areas for growth. Lower scores don't mean the relationship won't work — they indicate more areas where conscious effort and understanding are needed.

No! Synastry can be used for any relationship — romantic partners, friends, family members, business partners, or even parent-child dynamics. The planets and aspects interpreted may differ: for business, you'd focus more on Mercury (communication) and Saturn (responsibility), while for friendships, Jupiter (shared joy) and Moon (emotional connection) become more relevant.