Lunar Calendar

About Chinese Lunar Calendar, Solar Terms & Heavenly Stems

The Chinese Lunar Calendar (农历 / 阴阳历) is a lunisolar calendar that synchronizes lunar phases (synodic months) with the solar year (tropical year). Used for millennia across East Asia, it governs traditional festivals, agricultural cycles, and astronomical observations.

Lunisolar Synchronization & The 24 Solar Terms

• Synodic Month Calculations: A lunar month runs from one New Moon (朔) to the next, averaging approximately 29.53059 days. Months are either 29 days (Small Month) or 30 days (Big Month).
• Leap Months (闰月): Because 12 lunar months equal approximately 354 days (approx. 11 days shorter than the solar year), a leap month is inserted roughly every 2 to 3 years (7 leap months in 19 years) to prevent seasonal drift.
• The 24 Solar Terms (二十四节气): Points on the ecliptic spaced exactly 15 degrees apart, marking seasonal milestones including the Equinoxes, Solstices, and agricultural markers like Lichun (立春) and Qingming (清明).
• Sexagenary Cycle (干支): A 60-year cyclical naming system combining the 10 Heavenly Stems (天干) and 12 Earthly Branches (地支 - Zodiac Animals).

Frequently Asked Questions (FAQ)