Purnima (full moon) and Amavasya (new moon) are the two most significant tithis of the lunar month. Fasting, ritual bathing and charity, and pitru tarpan are all performed on these tithis. Every month turns around these two poles: Purnima closes Shukla Paksha (the bright half), and Amavasya closes Krishna Paksha (the dark half).
Why these two tithis matter so much
Purnima is when the Moon is at full illumination, sitting directly opposite the Sun. Traditionally, this is considered the best tithi for sattvic activities: charity, fasting, Satyanarayan Katha, and visiting holy rivers. A Purnima fast is sometimes called “chandraayan vrat” when done as part of a longer cycle, but the standalone monthly fast is the more common practice.
Amavasya is the opposite: no visible Moon. This is the tithi for pitru tarpan (offering water to ancestors), Shani puja, and in some families, a fast dedicated to removing obstacles. If you’ve ever wondered why your grandmother insists on not starting anything new on Amavasya, this is the reasoning. The energy is considered inward, reflective, better for closing things than beginning them.
2026 Purnima dates
January 3, February 1, March 3, April 1, May 1, May 30, June 29, July 29, September 26, October 25.
2026 Amavasya dates
January 18, February 17, March 18, April 17, May 16, July 14, August 12, September 10, October 10.
Some dates in August-September and June fall slightly out of the usual pattern in 2026 because of Adhik Maas (two Jyeshtha months). Dates for the rest of the year will be updated as soon as they’re added to the panchang engine. The always-updated list is available on the festival calendar.
What is Adhik Maas and why does it shift dates?
Every two to three years, the Hindu lunar calendar inserts an extra month called Adhik Maas (also called Purushottam Maas) to realign with the solar calendar. In 2026, this falls as a second Jyeshtha month. During Adhik Maas, some families avoid major ceremonies like weddings and grihapravesh, while others observe additional fasting and charity. The Purnima and Amavasya during Adhik Maas are still valid for regular monthly observances, but their dates look “off” if you’re comparing against a standard 12-month expectation.
The time zone trap for NRIs
Here’s something that catches people every month: a Purnima that falls on January 3 in India might still be January 2 in New York or January 4 in Auckland. The tithi begins and ends at a fixed astronomical moment, but the local calendar date it maps to depends on your time zone. If you’re fasting, you need the tithi timing for your city, not just the India date. A 10-hour difference between IST and US Eastern Time is enough to shift the observance by a full day.
How to check the tithi for your city
The exact start and end of a tithi can differ slightly by city, so before fasting or ritual bathing, confirm that day’s tithi by selecting your city on the panchang page. The page shows the tithi’s start and end time in your local time, so there’s no mental math involved.
The final call is yours
Observe vrats and rituals according to your family’s tradition and convenience. Some families follow the North Indian Purnimant calendar, others follow the South Indian Amant calendar, and the Purnima/Amavasya dates are the same in both. The difference between the two systems only affects which Purnima or Amavasya belongs to which named month.