Why two dates can both appear
A civil day starts at midnight. A lunar tithi starts when the angle between the Moon and Sun crosses a multiple of twelve degrees. Since those boundaries occur at different clock times, a tithi can begin on one date and end on the next. That is why our monthly calendar may mark two adjacent squares.
What Amavasai means in this calendar
The Amavasai tithi is the final twelve-degree interval before the Moon and Sun return to the same ecliptic longitude. Our listing shows the beginning and end of that interval. The new moon is the moment at its end.
What Pournami means in this calendar
The Pournami tithi covers the twelve-degree interval leading up to the Moon being opposite the Sun in ecliptic longitude. Its endpoint is the full moon. You can save the whole interval to your personal calendar from the Special Days page.
An interval is not a fasting instruction
Selecting a fasting day or a date for a particular ritual can depend on when the tithi is present, local sunrise and a tradition-specific rule. We do not label the beginning date of an astronomical interval as a universally correct observance date. Confirm the local practice before planning a ceremony.
Use the calendar to look ahead
Choose Amavasai or Pournami, select a month, and read both endpoints. Every time shown on this edition is in IST. The downloaded calendar event stores the actual instants, so your calendar application may display them in your own device timezone.