Calendar Basics

What Makes the Tibetan Calendar Unique?

The Tibetan calendar is a lunisolar system—it tracks both the Moon's phases (lunar) and the Sun's annual journey (solar). This places it in the same family as the Chinese, Hebrew, and Hindu calendars, but with its own distinctive characteristics rooted in the Kālacakra Tantra.

Three Key Principles

1. Lunar Days (tshes pa) — Each month has 30 lunar days, defined by the Moon's position relative to the Sun. Unlike solar days, these don't have fixed length.
2. Solar Synchronization — To keep months aligned with seasons, extra (intercalary) months are added when needed—about 7 times every 19 years.
3. Astronomical Calculation — Dates are computed mathematically from epoch values, not observed directly. This allows calendars to be calculated centuries in advance.

The Kālacakra Foundation

The Tibetan calendar derives from the Kālacakra ("Wheel of Time") Tantra, a Buddhist text dating to around the 10th century CE. The tantra contains detailed astronomical chapters that were refined and adapted by Tibetan scholars over centuries.

Key points about this origin:

• The calculations are siddhānta style (theoretical/computed), not observational
• Parameters were derived from Indian astronomical traditions
• Tibetan scholars developed multiple calculation traditions with refined values

Reading Tibetan Dates

A complete Tibetan date includes:

• Year: Element + Gender + Animal (from the 60-year cycle)
• Month: Number 1-12 (possibly with intercalary marker)
• Day: Lunar day 1-30

Continue to Months & Years →