What the sun sign, rising sign, elements, and zodiac compatibility mean, and how they're calculated — explained simply.
A birth chart (natal chart) is a snapshot of the sky at the exact date, time, and place you were born; it shows where the Sun, Moon, and planets sat along the zodiac. In astrological tradition, this chart is read as a symbolic language describing tendencies and potential, not destiny. The best-known layer is your sun sign: the sign the Sun occupied on your birth date. But a full chart is far richer than the sun sign alone.
How is the sun sign determined?
Quick answerYour sun sign is determined by which sign the Sun was in on the day you were born. The 12 signs each have a fixed date range (e.g. Aries: Mar 21–Apr 19). If you were born on a cusp day (right when one sign ends and another begins), only the date matters — not the time or your rising sign — and this tool handles cusp days correctly.
How is the rising sign calculated?
Quick answerYour rising sign is whichever sign is rising on the eastern horizon at the moment you were born. It takes three things to calculate: an exact birth date, exact birth time, and your birth location. At the moment of sunrise the rising sign is usually the same as your sun sign; it then moves to the next sign roughly every ~2 hours. An exact degree needs an ephemeris and a daylight-saving-time correction.
This tool uses a simplified method that treats sunrise as a reference point and advances the sign based on your birth time. The result usually lands correctly between neighboring signs; if your birth time is near a boundary, your true rising sign could be the sign just before or after. That's why the result is shown as "approximate," and we recommend timeless mode if your birth time is uncertain, so you can see both candidate signs.
What does zodiac compatibility (synastry) look at?
Quick answerClassic zodiac compatibility looks at two signs' element (fire, earth, air, water), modality (cardinal, fixed, mutable), and their angle on the zodiac wheel (same sign, sextile, trine, square, opposition). The same element (trine) and elements that reinforce each other (fire-air, earth-water) tend to score highest. Real compatibility isn't determined by a single sign but by the interaction of two full charts.