What this calculator does
This calculator places two sets of Big Three signs side by side. It also identifies the associated Fire, Earth, Air or Water elements. It does not calculate planetary aspects or full synastry and does not assign a compatibility percentage. Use the comparison as an entertainment or reflection prompt, not as a decision about a relationship.
Formula, assumptions and sources
Tropical zodiac. Sun and Moon use Astronomy Engine. Ascendant uses local sidereal time and approximate obliquity. Enter accurate coordinates and the historical UTC offset; there is no automatic timezone lookup. Astrology interpretations are entertainment, not scientific predictions. Calculation library. This is a Big Three element comparison, not full synastry.
Worked example
This example uses the initial values shown in the form. It is illustrative and is not a saved personal result.
Example inputs
- Birth date
- 1995-06-15
- Birth time (local, 24-hour)
- 12:00
- UTC offset at birth
- 0
- Birthplace latitude
- 51.5074
- Birthplace longitude
- -0.1278
- Birth date
- 1995-06-15
- Birth time (local, 24-hour)
- 12:00
- UTC offset at birth
- 0
- Birthplace latitude
- 51.5074
- Birthplace longitude
- -0.1278
Example result
| Placement | Person one | Person two | Element connection |
|---|---|---|---|
| sun | Gemini | Gemini | Shared Air element |
| moon | Capricorn | Capricorn | Shared Earth element |
| rising | Virgo | Virgo | Shared Earth element |
Use these placements for reflection. Shared or different elements do not measure real-world relationship compatibility.
Frequently asked questions
Is this a full synastry chart?
No. It compares Sun, Moon and Rising placements only. Full synastry requires additional planetary positions and aspects.
Does a shared element mean two people are compatible?
No. These labels do not establish real-world compatibility or predict relationship outcomes.
Method and example checked 4 November 2026. How we check calculations