Methodology & Tools

This page provides technical detail about the calculations and tools behind ZodiAge's features. For editorial standards and content policy, see the Editorial Policy.

Age Calculation

Exact age is computed using precise date arithmetic that accounts for leap years, varying month lengths (28–31 days), and optional timezone offsets when birth time is provided. The counter updates every second in real time.

Western Zodiac Calculations

ZodiAge uses the Tropical Zodiac — the standard in Western astrology, aligned to the vernal equinox. Sun sign boundaries follow the traditional calendar dates. Moon signs use simplified lunar position algorithms. Rising signs require birth time and are calculated from the ecliptic degree rising on the eastern horizon.

Chinese Zodiac Calculations

Animal assignment uses accurate Lunar New Year boundaries (not January 1st). The Five Elements (Wood, Fire, Earth, Metal, Water) are derived from the 10-year Heavenly Stem cycle. Yin/Yang polarity is based on the animal's position in the 12-year cycle.

Tarot

Daily card selection uses a seeded random algorithm based on the current date, ensuring the same card appears throughout a single day. The 3-card spread uses a separate seed for temporal variety.

Data Sources

Astronomical data is cross-referenced with NASA, the International Astronomical Union (IAU), and the U.S. Naval Observatory. Life expectancy statistics are drawn from WHO data. Historical astrological references cite Encyclopædia Britannica and academic sources.