Discover the astrological compatibility between you and your partner. Our synastry calculator analyzes the relationship dynamics between two birth charts to reveal love compatibility, marriage potential, and relationship strengths.
Enter both partners' birth details to compare verified planetary positions and inter-chart aspects. The compatibility index is an astrological interpretation, not a scientific prediction.
Your birth details are used to calculate this result. Guest calculations are not saved to an account; after viewing the result, you can choose to sign in and save both profiles for future comparisons.
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Synastry is the ancient art of comparing two birth charts to understand relationship dynamics
Synastry is the branch of astrology that studies relationships by comparing two birth charts. It reveals how two people's planets interact with each other, showing areas of harmony, challenge, and growth potential.
By overlaying one person's planetary positions onto another's chart, synastry helps understand the dynamics of any relationship - romantic, familial, or professional.
These planetary connections reveal different dimensions of your relationship
How well your core identities and life purposes align
Foundation of the relationship
Emotional connection and how you nurture each other
Emotional harmony and security
Romantic attraction and sexual compatibility
Passion and physical chemistry
Communication styles and intellectual connection
Understanding and mental rapport
Long-term commitment and relationship stability
Endurance and lasting bonds
Growth, expansion, and shared vision for the future
Mutual growth and optimism
Aspects are the angular relationships between planets in two charts
| Aspect | Meaning | Effect |
|---|---|---|
| Conjunction (0°) | Blending of energies - can be harmonious or intense depending on planets | Strong |
| Trine (120°) | Natural harmony and easy flow of energy between charts | Harmonious |
| Sextile (60°) | Opportunities for growth and positive interaction | Supportive |
| Square (90°) | Dynamic tension that can create growth through challenge | Challenging |
| Opposition (180°) | Polarity that attracts but may require balance | Magnetic |
Synastry can reveal insights about any type of relationship
Love, marriage, and long-term relationships
Emotional, romantic, and sexual compatibility
Platonic relationships and social connections
Shared interests and mutual understanding
Parent-child, siblings, and extended family
Emotional bonds and familial dynamics
Business partnerships and work relationships
Collaboration and professional synergy
Use our free synastry calculator above to reveal the astrological dynamics between you and your partner. Get instant insights into your compatibility!
Calculate Synastry NowEverything you need to know about synastry and astrological compatibility
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.
Planetary longitudes and aspect orbs are calculated with Swiss Ephemeris from each person’s birth date, time, and location. The resulting compatibility score is a transparent astrological index, not a scientifically validated measure of a relationship.
You need the birth date, birth time, and birth location for both people. Birth time matters because the Moon and other planetary positions continue moving throughout the day. Avoid inventing a time: an approximate time can change close aspects and therefore the interpretation.
Synastry compares the planetary positions in two separate birth charts to interpret how two people may interact. A composite chart is a different calculation built from planetary midpoints. This free calculator provides synastry aspects; it does not present a composite chart.
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.