Paksha (or pakṣa:
Sanskrit: पक्ष) refers to a
fortnight or a
lunar phase in a month of the
Hindu lunar calendar.
Literally meaning "side",
 a paksha is the period either side of the
Full Moon Day (
lunar month in the Hindu calendar has two fortnights, and begins with the
New moon, (
Amavasya). The lunar days are called
tithis and 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 New Moon Day and Full Moon Day is called “Gaura Paksha” or Shukla Paksha, the period of the brightening moon (
waxing moon), and the second fortnight of the month is called “Krishna Paksha”, or Vadhya Paksha, the period of the fading moon (
 Nimach Panchang begin new lunar month from first day of Krishna Paksha while Gujarat Panchang begin new lunar month from first day of Shukla Paksha.