Frequently Asked Questions
Everything you need to know about zodiac compatibility, synastry algorithms, and finding your celestial match.
A zodiac compatibility calculator is an astrological analysis tool that compares the sun signs, elemental balances, modalities, and celestial aspects between two individuals. By evaluating these cosmic coordinates, the calculator calculates a nuanced synastry report detailing emotional resonance, passion, communication synergy, and areas of friction with actionable remedies.
Yes, ZodiacDuo is 100% free. Our zodiac compatibility calculator free version offers unlimited compatibility readings with zero sign-ups, no email requirements, no mobile app downloads, and no hidden subscriptions. All calculations run instantly in your browser with full privacy.
To find out if your zodiac sign is compatible, simply select your sign (or enter your date of birth) in the Person 1 card and your partner's sign or birthdate in the Person 2 card, then click "Reveal Cosmic Compatibility". You will immediately receive a 0–100% overall score, detailed dimension meters, key relationship strengths, and friction fixes.
Zodiac compatibility astrology (traditionally known as synastry) is the branch of astrology dedicated to studying interpersonal relationships. It compares how the elemental traits (Fire, Earth, Air, Water), modalities (Cardinal, Fixed, Mutable), and planetary rulerships of two people interact to produce harmony, creative tension, or mutual growth.
Our zodiac compatibility calculator percentage evaluates elemental synergy (such as Fire + Air fanning mutual passion or Earth + Water offering fertile grounding), modal dynamics, and geometric aspects like Trines, Sextiles, Oppositions, and Squares. These weights are synthesized into an overall score and broken down across romance, intellect, trust, and long-term commitment.
Yes! While many use it for romance, our system functions seamlessly as a parent child zodiac compatibility calculator and family zodiac compatibility calculator. By comparing an adult's sign with a child's or sibling's sign, you uncover emotional needs, communication styles, and natural bonding triggers. See our dedicated parent-child guide for more.
A zodiac compatibility calculator for marriage provides valuable diagnostic insights into core values, lifestyle pacing, and emotional longevity. While astrology illuminates natural affinities and potential friction points, marital success ultimately depends on mutual commitment, respect, and open communication. Read more in our marriage compatibility guide.
Sun signs represent your conscious ego and core life path. A full zodiac chart compatibility calculator also includes Moon (emotions), Venus (love language), and Mars (passion). Our calculator uses accurate solar transit boundaries and elemental synastry to deliver the most reliable sun-sign analysis available online without needing exact birth times or coordinates.