Amanta and Purnimanta months
Two ways of ending a Hindu lunar month. Amanta months end at the new moon (Amavasya), as in Gujarat, Maharashtra and the South; purnimanta months end at the full moon (Purnima), as in most of North India.
Also known as: Amavasyant, Purnimant, Amavasyanta
Both systems use the same twelve month names and the same tithis. They differ only in where the month starts. In amanta reckoning, a month runs from the day after Amavasya to Amavasya. In purnimanta reckoning, it runs from the day after Purnima to Purnima, so each month opens with its dark half.
As a result, the bright half always carries the same month name in both systems, while the dark half is named one month ahead in purnimanta calendars. Janmashtami, for example, is Shravana Krishna Ashtami in amanta calendars and Bhadrapada Krishna Ashtami in purnimanta ones.
Purnimanta is followed across most of North India, including Uttar Pradesh, Bihar, Madhya Pradesh, Rajasthan and Punjab. Amanta is followed in Gujarat, Maharashtra, Goa, Karnataka, Andhra Pradesh and Telangana. A common worry is that the two give different festival dates. They don’t: only the month label changes, and our Panchang shows both.