The Tibetan calendar (Tibetan: ལོ་ཐོ, Wylie: lo-tho), or Tibetan lunar calendar, is a lunisolar calendar, that is, the Tibetan year is composed of either 12 or 13 lunar months, each beginning and ending with a new moon. A thirteenth month is added every two or three years, so that an average Tibetan year is equal to the solar year.[1] The Phukpa calendar is the main Tibetan calendar, and the Karma Kagyu's Tsurluk calendar is also in current use.
The Tibetan New Year celebration is Losar (Tibetan: ལོ་གསར་, Wylie: lo-gsar), which falls either in the months of February or March, in the Gregorian calendar. There were many different traditions in Tibet to set the date of first day of the new year. The first day of the new year also aligns with the third Hor (Mongolian) month in other almanacs, while the dates of the Mongolian calendar are the same as the Tibetan calendar.[2]
Every month, certain dates in the Tibetan calendar have special significance for Tibetan Buddhist practices.[3][4], as do certain months of the Tibetan calendar year when the anniversaries of events from Shakyamuni Buddha's life correspond, such as Saga Dawa of the Tibetan fourth month.