Lunar Month System (Purnimant / Amanta)मास प्रणाली

There are two regional conventions for where a Vedic lunar month begins and ends: Purnimant (month ends at full moon, used in North India) and Amanta (month ends at new moon, used in South India). Both describe the same underlying Moon cycle, just with a different starting/ending point.

In practice

This mostly affects which calendar name a given day falls under near the month boundary — the day itself, its Tithi, Nakshatra, and all other Panchang data are identical regardless of which system is used to name the month.

How it's calculated

A fixed regional convention, not an astronomical calculation — the system in use is shown in parentheses after the month name (e.g. "Ashadha (Shukla Paksha, purnimant)").