What this calculator does
Your Big Three are three distinct placements in a tropical birth chart. The Sun and Moon signs are calculated from their ecliptic longitudes. The Rising sign is the zodiac sign on the eastern horizon at the birth time and place. Enter the historical UTC offset, including any daylight-saving adjustment, rather than today’s offset.
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.
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
Example result
Positions: Sun 83.93°, Moon 297°, Ascendant 175.19°. Birth instant: 1995-06-15T12:00:00.000Z. An accurate time is essential for Rising.
Frequently asked questions
Can I calculate my Rising sign without a birth time?
Not reliably. A different birth time can change the Ascendant. This tool requires a time rather than guessing one.
Why does another astrology website give different signs?
Check the time zone, daylight saving, birth coordinates and zodiac system. This tool uses the tropical zodiac; sidereal results can differ.
Method and example checked 4 November 2026. How we check calculations