The
Thai lunar calendar (, , , literally,
Specific days according to lunar norms), or
Tai calendar, is a
lunisolar Buddhist calendar. It is used for calculating lunar-regulated holy days. Based on the
SuriyaYatra, with likely influence from the traditional Hindu
Surya Siddhanta, it has its own unique structure that does not require the Surya Siddhanta to calculate. Lunisolar calendars combine
lunar and
solar calendars for a nominal
year of 12
months. An extra day or an extra 30-day month is
intercalated at regular intervals.