Synastry Chart Calculator (Relationship Compatibility)
Compare two birth charts with dual concentric SVG wheels, romantic chemistry scores, and comprehensive planetary inter-aspects.
TL;DR: Synastry Chart Calculator overlays two birth charts to evaluate emotional harmony, communication, and romantic chemistry in your browser.
PERSON A
PERSON B
Overall Synastry Match Score
98%
Neutral — Aries (Fire) & Scorpio (Water)
💖 Romantic Chemistry98%
🌊 Emotional Safety96%
🧠 Intellectual Sync99%
🪐 Long-Term Loyalty95%
Dual-Wheel Synastry Chart
● Person A (Inner Ring)
● Person B (Middle Ring)
Inter-Chart Planetary Connections
| Person A | Aspect | Person B | Nature | Orb |
|---|---|---|---|---|
| Sun (A) | △ Trine | Mercury (B) | Effortless Harmonic Flow | 2.3° |
| Sun (A) | □ Square | Venus (B) | Dynamic Friction / Catalytic Growth | 1.6° |
| Sun (A) | □ Square | Mars (B) | Dynamic Friction / Catalytic Growth | 2.6° |
| Sun (A) | ⚹ Sextile | Uranus (B) | Supportive / Opportunistic | 0.2° |
| Sun (A) | △ Trine | Pluto (B) | Effortless Harmonic Flow | 1.6° |
| Moon (A) | △ Trine | Jupiter (B) | Effortless Harmonic Flow | 5.2° |
| Moon (A) | ⚹ Sextile | Saturn (B) | Supportive / Opportunistic | 5.0° |
| Mercury (A) | △ Trine | Mercury (B) | Effortless Harmonic Flow | 5.1° |
| Mercury (A) | □ Square | Venus (B) | Dynamic Friction / Catalytic Growth | 4.3° |
| Mercury (A) | □ Square | Mars (B) | Dynamic Friction / Catalytic Growth | 0.1° |
| Mercury (A) | ⚹ Sextile | Uranus (B) | Supportive / Opportunistic | 2.6° |
| Mercury (A) | ⚹ Sextile | Neptune (B) | Supportive / Opportunistic | 5.0° |
| Mercury (A) | △ Trine | Pluto (B) | Effortless Harmonic Flow | 1.2° |
| Venus (A) | ☍ Opposition | Sun (B) | Magnetic Polarity / Balance | 0.4° |
| Venus (A) | □ Square | Jupiter (B) | Dynamic Friction / Catalytic Growth | 6.8° |
| Venus (A) | △ Trine | Neptune (B) | Effortless Harmonic Flow | 6.6° |
| Mars (A) | △ Trine | Mercury (B) | Effortless Harmonic Flow | 6.8° |
| Mars (A) | □ Square | Venus (B) | Dynamic Friction / Catalytic Growth | 6.0° |
| Mars (A) | □ Square | Mars (B) | Dynamic Friction / Catalytic Growth | 1.8° |
| Mars (A) | ⚹ Sextile | Uranus (B) | Supportive / Opportunistic | 4.3° |
| Mars (A) | ⚹ Sextile | Neptune (B) | Supportive / Opportunistic | 3.3° |
| Mars (A) | △ Trine | Pluto (B) | Effortless Harmonic Flow | 2.8° |
| Jupiter (A) | ⚹ Sextile | Sun (B) | Supportive / Opportunistic | 5.2° |
| Jupiter (A) | □ Square | Saturn (B) | Dynamic Friction / Catalytic Growth | 1.0° |
| Saturn (A) | △ Trine | Sun (B) | Effortless Harmonic Flow | 7.8° |
| Saturn (A) | □ Square | Mars (B) | Dynamic Friction / Catalytic Growth | 4.2° |
| Saturn (A) | ⚹ Sextile | Neptune (B) | Supportive / Opportunistic | 0.9° |
| Saturn (A) | △ Trine | Pluto (B) | Effortless Harmonic Flow | 5.3° |
| Uranus (A) | □ Square | Moon (B) | Dynamic Friction / Catalytic Growth | 6.3° |
| Uranus (A) | ⚹ Sextile | Mercury (B) | Supportive / Opportunistic | 3.7° |
| Uranus (A) | ☌ Conjunction | Uranus (B) | Harmonizing / Unified Blend | 1.2° |
| Uranus (A) | ☌ Conjunction | Neptune (B) | Harmonizing / Unified Blend | 6.3° |
| Uranus (A) | ⚹ Sextile | Pluto (B) | Supportive / Opportunistic | 0.2° |
| Neptune (A) | □ Square | Moon (B) | Dynamic Friction / Catalytic Growth | 0.1° |
| Neptune (A) | ☌ Conjunction | Uranus (B) | Harmonizing / Unified Blend | 7.6° |
| Neptune (A) | ☌ Conjunction | Neptune (B) | Harmonizing / Unified Blend | 0.0° |
| Pluto (A) | ☌ Conjunction | Mercury (B) | Harmonizing / Unified Blend | 5.9° |
| Pluto (A) | ⚹ Sextile | Uranus (B) | Supportive / Opportunistic | 3.4° |
| Pluto (A) | ⚹ Sextile | Neptune (B) | Supportive / Opportunistic | 4.2° |
| Pluto (A) | ☌ Conjunction | Pluto (B) | Harmonizing / Unified Blend | 2.0° |
What Is a Synastry Chart in Relationship Astrology?
In relationship astrology, a synastry chart compares two individual natal birth charts by overlaying one partner's planetary positions onto the other's. This reveals planetary inter-aspects (such as Sun conjunct Moon or Venus trine Mars) that describe romantic chemistry, communication ease, emotional security, and potential growth challenges.
How to Use the Synastry Chart Calculator
Our Synastry Chart Calculator utilizes deterministic astronomical ephemeris formulas to calculate accurate planetary positions, signs, degrees, and aspects right inside your web browser.
- Input the birth date, exact time, and birthplace for Person A and Person B.
- Click 'Calculate Synastry Compatibility' to generate the dual-ring celestial wheel.
- Review the overall Compatibility Score, elemental harmony breakdown, and inter-aspect connection table.
Astrology & Personal Reflection Disclaimer
Astrological interpretations are provided for entertainment, personal reflection, and self-exploration. They do not constitute scientific fact, financial, medical, or relationship guarantees.
100% Client-Side Privacy Guarantee
All birth details and astrological calculations run locally in your web browser. No personal birth times, dates, or cities are transmitted to external servers.
Frequently Asked Questions
- A synastry chart is a relationship astrology technique that overlays two individuals' birth charts to inspect how their planets interact, highlighting areas of natural flow, attraction, and constructive friction.
- Synastry evaluates angular cross-aspects between both charts (e.g., Person A's Sun to Person B's Moon), elemental balance (Fire, Earth, Air, Water), and house overlays to calculate an overall synergy score.
- Synastry compares two separate individuals interacting with one another. A composite chart mathematically calculates midpoints between both charts to create a single third chart representing the relationship itself as an entity.
- Astrologers traditionally look for Sun-Moon aspects (emotional bonding), Venus-Mars aspects (erotic and romantic chemistry), and Venus-Ascendant connections (mutual aesthetic attraction).
- No. In astrology, challenging aspects like squares and oppositions provide sexual tension, mutual motivation, and growth opportunities that prevent complacency when balanced with supportive trines.
- Yes. Synastry can be applied to any relationship dynamic. Mercury aspects highlight intellectual communication, while Saturn and Jupiter aspects illuminate business reliability and shared values.
- Exact birth times determine both partners' Moon degrees (which move ~13° daily), Ascendant degrees, and house overlays, which are critical for precise synastry inter-aspects.
- Venus conjunct Mars is one of the classic markers of passionate romantic and physical attraction, blending affection, desire, and aesthetic appreciation.
- Saturn aspects provide the structural glue, loyalty, duty, and endurance necessary for long-term relationships, marriages, and dependable partnerships.
- No. All calculations run strictly in-browser using client-side JavaScript. Neither partner's private birth information is stored, logged, or transmitted.
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