Synastry Chart Calculator & Birth Chart Compatibility 💫
Enter two birth charts to discover your astrological synastry — planetary aspects, house overlays, and a detailed compatibility reading.
Same sign between both charts = natural resonance · Different sign = growth edge
Synastry Chart Calculator, Free Relationship Compatibility
A Synastry Chart Calculator goes far beyond simple sun-sign horoscopes. By calculating and comparing two complete birth charts, our tool reveals the exact cosmic dynamics, friction points, and deep emotional connections between you and your partner.
If you’ve ever wondered why you instantly click with someone or why certain relationships feel challenging, this Astrology Compatibility Calculator provides the answers by analyzing planetary aspects, exact orbs, and house overlays.
How to Read the Overall Compatibility Score
As soon as you enter both birth details, our calculator generates an Overall Compatibility Score (out of 100) alongside a clear relationship verdict. Below the main score gauge, your cosmic chemistry is broken down into three distinct categories:
- Harmonious (Green): The areas where your energies naturally flow together, bringing ease, affection, and mutual understanding (like Trines and Sextiles).
- Tense (Red): The friction points. Don't panic! Tension creates passion and pushes both partners to grow. A healthy relationship needs a balance of harmony and tension.
- Neutral (Gray): Subtler connections (like certain Conjunctions) that amplify energy depending on how you both handle them.
The Big Three Comparison (☉ ☽ ⬆)
Our calculator aligns your Sun, Moon, and Ascendant (Rising Sign) side-by-side. The Sun represents your core egos, the Moon reveals your deepest emotional needs, and the Ascendant dictates how you approach the world. Comparing these three pillars instantly highlights whether you share fundamental life approaches or if you'll need to compromise on your core emotional languages.
Understanding House Overlays
Planetary aspects tell us how you interact, but House Overlays reveal where this interaction happens. Our calculator generates 12 detailed cards mapping out themes like Money & Values, Home & Roots, and Intimacy.
- ✓ Resonance: If you share the same sign in a specific house, you will see a green Resonance badge. This means you have a natural, effortless understanding in that area of life.
- ↔ Growth Edge: Different signs in a house trigger an orange Growth Edge badge. This indicates an area where your differing perspectives will challenge you to expand and learn from each other.
Key Planetary Aspects & Exact Orbs
At the bottom of your report, you'll find a color-coded list of your most important planetary aspects. We calculate the exact mathematical angle between your planets. Pay special attention to the "Exact" badge accompanied by a low orb degree (e.g., 0.36°)—these represent the strongest, most undeniable energetic ties between you and your partner!
Synastry is Just the Beginning
Did you know your detailed birth chart?
Calculate Your Full Birth ChartFrequently Asked Questions
What is a Synastry Chart?
Synastry is the branch of astrology that studies relationships by overlapping and comparing the natal charts of two individuals to determine their overall compatibility.
Do I need exact birth times for compatibility?
Yes. While you can calculate basic planetary aspects without a birth time, exact birth times are strictly required to calculate the Ascendant and accurate House Overlays.
What does a low compatibility score mean?
A lower score simply means there is more "Tension" (Growth Edge) than "Harmony." It doesn't mean the relationship will fail; it means you will both need to put in more conscious effort to understand each other's differences.
Which planet is most important for love?
Venus dictates how we express affection, Mars rules physical chemistry and primal desire, and the Moon governs emotional safety. Strong connections between these planets indicate profound romantic compatibility.