Zodiac Compatibility Calculator
Compare two sun signs and see where you click, where you clash, and what each of you brings out in the other.
Sun-sign compatibility is the part of astrology almost everyone has tried, and it is also the simplest layer of it. Your sun sign describes the core of how you move through the world. Put two of them side by side and you can see where two styles meet easily, where they grind, and where each pushes the other to change. This calculator does exactly that and shows its working.
What it cannot do is judge a relationship. Astrologers compare couples through synastry, which lays two complete birth charts over each other: the Moon for emotional needs, Venus for how each of you loves, Mars for desire and conflict, the Ascendant, and the aspects between all of them. Two people with a "hard" sun pairing can have closely matched Moons, and the reverse. For that full comparison, use Partner Match in the app.
How it works
Enter two birth dates, or pick two signs if you already know them. A date is converted to its tropical sun sign using the standard date ranges (Aries from March 21, Taurus from April 20, and so on). Every result then follows from three facts about the pair:
Element. Each sign belongs to fire, earth, air or water. Same element means shared instincts. Fire with air and earth with water are complementary. Any other mix is contrasting.
Modality. Cardinal signs start things, fixed signs sustain them and mutable signs adapt. Two signs of the same modality understand each other's pace but compete on it.
Aspect. The angle between the signs, counted in steps of 30° around the wheel: same sign (0°), semi-sextile (30°), sextile (60°), square (90°), trine (120°), quincunx (150°) or opposition (180°).
How the scores are built
There are no hidden weights and no random percentages. Each fact adds fixed points to three scores, and each score is the plain sum, out of 10. Harmony is how easily you get along, friction is how much you rub against each other, and growth is how much you push each other to change. High friction is not a bad result; squares score low on harmony and high on growth for a reason.
- Same element: H 4 · F 0 · G 1
- Complementary elements: H 3 · F 1 · G 2
- Contrasting elements: H 1 · F 2 · G 3
- Same modality: H 0 · F 2 · G 2
- Different modalities: H 1 · F 0 · G 1
- Same sign (0°): H 3 · F 1 · G 1
- Semi-sextile (30°): H 1 · F 1 · G 3
- Sextile (60°): H 3 · F 0 · G 2
- Square (90°): H 0 · F 6 · G 5
- Trine (120°): H 5 · F 0 · G 1
- Quincunx (150°): H 1 · F 2 · G 3
- Opposition (180°): H 2 · F 3 · G 3
For example, Aries and Leo are both fire (H 4, F 0, G 1), cardinal and fixed (H 1, F 0, G 1), and a trine apart (H 5, F 0, G 1): harmony 10, friction 0, growth 3. Because the three facts depend only on how far apart the signs sit, every pair at the same distance shares the same scores. What makes each pair its own is the reading, written separately for all 78 combinations.
Born on a cusp?
The Sun changes sign around the 19th to the 23rd of each month, and the exact moment moves by up to a day from year to year. If you were born in that window, the calculator flags it. To be certain, check the Big Three calculator, which uses your full birth date, time and place and also gives your Moon and rising sign.
Frequently asked
How does this zodiac compatibility calculator work?
It finds each person's sun sign, from a birth date or a picked sign, and measures the distance between the two signs on the zodiac wheel. That distance fixes the aspect (same sign, semi-sextile, sextile, square, trine, quincunx or opposition), and the signs' elements and modalities fix the other two factors. Each factor adds published points to harmony, friction and growth scores, and you get a reading written for your exact pair.
Which zodiac signs are most compatible?
By the rules on this page, pairs a trine apart (same element, such as Aries and Leo or Taurus and Virgo) score highest on harmony, followed by sextiles and same-sign pairs. Squares, such as Aries and Cancer, score highest on friction and growth. Easy is not the same as good, though. Many lasting couples have a square between their suns, and many trines drift apart through complacency.
Is sun-sign compatibility accurate?
Treat it as a conversation starter, not a prediction. A large 2007 study of about ten million married couples in England and Wales found that no sun-sign pairing married more often than chance would predict. Astrologers would add that the sun is one factor among many; the Moon, Venus, Mars and Ascendant matter at least as much for how two people live together.
What if one of us was born on a cusp?
Nobody is technically both signs. The Sun is in one sign or the other at the moment of birth, but the changeover date shifts slightly from year to year and depends on the time of day. If a birth date falls between the 19th and 23rd of a month, the calculator flags it and names the neighboring sign. The Big Three calculator settles it with the exact birth time and place.
Why do opposite signs attract?
Opposite signs sit 180° apart and share an axis: Aries and Libra (self and partner), Taurus and Scorpio (mine and ours), Cancer and Capricorn (home and career), and so on. They always share a modality and a complementary element, so each partner carries the qualities the other underplays. That produces strong attraction and recurring tug-of-war, which is why oppositions score in the middle on all three measures.
What does a full compatibility reading look at?
Synastry compares every planet in one chart with every planet in the other. The Moon shows whether your emotional needs fit, Venus and Mars show attraction and how you handle desire and conflict, and the Ascendant shows first impressions and daily style. Partner Match in the Arcana Origin app runs that comparison from both birth dates, times and places. This page is free, needs no sign-up and runs entirely in your browser.
Compare the whole charts, not just the suns
Partner Match in the Arcana Origin app lays both birth charts side by side: Moon, Venus, Mars, Ascendant and every aspect between you.
Cast your full reading →