Paksha (Sanskrit: पक्ष, romanized: pakṣa) refers to a fortnight or a lunar phase in a month of the Hindu lunar calendar.[1][2]
Literally meaning "side",[3] a paksha is the period either side of the purnima (full moon day). A lunar month in the Hindu calendar has two fortnights, and begins with the purnima (new moon). The lunar days are called tithis; each month has 30 tithis, which may vary from 20 – 27 hours. A paksha has 15 tithis, which are calculated by a 12 degree motion of the moon. The first fortnight between the new moon day and the full moon day is called the Gaura Paksha or Shukla Paksha (lit. 'white/bright/golden side'), the period of the brightening moon (waxing moon), and the second fortnight of the month is called the Vadhya Paksha or Krishna Paksha (lit. 'dark/black side'), the period of the fading moon (waning moon).[1][4] The Neemuch calendar begin a new lunar month from first day of Krishna Paksha, while the Gujarat calendar begins a new lunar month from the first day of Shukla Paksha.