Zodiac Compatibility Calculator
Choose two signs, or type two birth dates to find the sun signs. The result names the relation between them.
How sun signs are compared
Astrology compares two sun signs by where they sit on the zodiac wheel. Signs four apart share an element, such as Aries and Leo, both fire, and are called trine. Signs three apart share a modality but not an element, and are called square. Opposite signs face each other across the wheel. Each distance has a traditional character, and the reading describes it.
The element pairs matter too. Fire and air are read as feeding each other, and so are earth and water. Fire with water, or air with earth, is the contrast to work with. Cardinal, fixed and mutable signs differ in how they start, hold and change.
If a birth date falls on a day when the Sun changed sign, the tool says so and lets you pick. Sun signs are only one layer; synastry compares whole charts.
What each relation means
| Relation | Signs apart | Example | In tradition |
|---|---|---|---|
| Same sign | 0 | Leo and Leo | Instant recognition, shared blind spots |
| Neighbours | 1 | Gemini and Cancer | Different elements side by side, learning each other |
| Sextile | 2 | Aries and Gemini | Friendly, compatible elements, easy talk |
| Square | 3 | Aries and Cancer | Friction that pushes both to grow |
| Trine | 4 | Aries and Leo | Same element, natural ease |
| Quincunx | 5 | Aries and Virgo | Little in common, steady adjusting |
| Opposite | 6 | Taurus and Scorpio | Strong pull between mirror images |
Worked examples
- Aries and Leo, four signs apart:
trineBoth are fire signs. - Aries and Cancer, three apart:
square - Taurus and Scorpio, across the wheel:
opposite - Gemini and Cancer, side by side:
neighbours - Elements of Aries and Leo:
same element
How this is calculated
Signs are counted around the zodiac: 0 apart same sign, 1 neighbours, 2 sextile, 3 square, 4 trine, 5 quincunx, 6 opposite. Elements: same, compatible (fire-air, earth-water) or contrasting. Modalities: same or different. A birth date gives the sun sign from a solar longitude series (Meeus ch. 25); on a day the Sun changed sign both signs are offered. No score.