What are the 60 combinations in Four-Pillar astrology?

The 60 combinations are the 'sixty Jia-Zi' (the 60 stem-branch pairs). They are the backbone of the Chinese calendrical system and of Four-Pillar astrology—representing the smallest complete cycle of time and the elemental signatures of specific moments.

Structure and role:
The ten Heavenly Stems pair in order with the twelve Earthly Branches to create 60 unique combinations (e.g., Jia-Zi, Yi-Chou, Bing-Yin, …, Gui-Hai). Each pair is used to designate years, months, days and hours, so any given birth moment maps precisely onto a unique Jia-Zi pair.

Importance in astrology:
• Basic unit of fate: The four pillars (year, month, day, hour) are each a specific Jia-Zi. Those four pairs are the core input for any BaZi reading.
• Refined elemental expression: Each Jia-Zi carries both the regular five-element attribute and the Na-Yin poetic element, adding texture to interpretation.
• Foundation for luck cycles: Major luck cycles (Da Yun) and annual influences are read through the sequence of Jia-Zi, connecting a static chart to dynamic time.
• Calendar and destiny link: The sixty-pair cycle embodies the 'heaven-human correspondence' idea—people born under different Jia-Zi inherit different cosmic tones that shape their life tendencies.