Zodiac Sign & Moon Phase

The calculator uses traditional tropical zodiac date boundaries, which are the most widely recognized in Western astrology. These boundaries divide the year into 12 equal 30-degree segments of the ecliptic, each associated with a specific date range. Note that due to the precession of the equinoxes, there is a slight offset between tropical and sidereal zodiac systems; this calculator uses the tropical system (Western astrology).

The moon phase is calculated using the Julian Day Number of your birth date. We compute the number of days since a known reference new moon (January 6, 2000 at 18:14 UTC) and divide by the synodic month length (29.53058867 days). The remainder gives the lunar age — the number of days since the last new moon — which maps directly to one of eight primary moon phases (New Moon, Waxing Crescent, First Quarter, Waxing Gibbous, Full Moon, Waning Gibbous, Last Quarter, Waning Crescent). The illumination percentage is derived from the phase angle using the cosine function.

No. All zodiac sign mapping, Chinese zodiac determination, and moon phase calculations happen 100% locally in your browser using JavaScript. No date, personal information, or calculation data is ever uploaded, logged, or stored. Your birth details never leave your device.

The Chinese zodiac (Shengxiao) is a 12-year repeating cycle of animals: Rat, Ox, Tiger, Rabbit, Dragon, Snake, Horse, Goat, Monkey, Rooster, Dog, and Pig. Your Chinese zodiac animal is determined by your birth year according to the traditional cycle. Each animal is associated with specific personality traits and compatibility patterns that complement the Western zodiac profile.

Yes. After entering your birth date and viewing your results, the tool automatically displays today's moon phase alongside your birth moon phase for comparison. You can also simply enter today's date to get just the current moon phase information.

The four zodiac elements (Fire, Earth, Air, Water) describe core temperamental qualities. Fire signs (Aries, Leo, Sagittarius) are passionate and dynamic. Earth signs (Taurus, Virgo, Capricorn) are grounded and practical. Air signs (Gemini, Libra, Aquarius) are intellectual and communicative. Water signs (Cancer, Scorpio, Pisces) are emotional and intuitive. Each element includes three signs separated by a 120-degree trine aspect.

Yes. The calculator is fully responsive and works on any device with a modern browser. The celestial phase chart and result cards adapt to smaller screens while maintaining readability.

Compatibility matches are based on traditional astrological synastry — the relationships between signs by element and modality. Fire signs pair well with Air signs (which fuel fire), Earth signs pair with Water signs (which nourish earth), and signs of the same quality (Cardinal, Fixed, Mutable) often share complementary approaches to life. The tool shows four traditional best matches for each sign.