Calendar foundations · begin here
What is a tithi?
Tithi is the most useful new calendar word to learn first.
A lunar month in thirty parts
Each 12-degree change in the Moon’s angle from the Sun is one tithi.
One complete cycle is 360 degrees. Because 360 ÷ 12 = 30, one lunar month contains thirty tithis.
A tithi lasts about one day. The Moon–Sun angle changes continuously, so a tithi can begin in the morning, afternoon, evening, or night.
Tithi is important because it is one of the calendar factors used to set dates for specific religious and cultural observances.
The visible Moon phase gives a helpful clue, but the exact tithi comes from the Moon–Sun angle.
Three different timing ideas
A date, a tithi, and a sunrise label have different boundaries.
Midnight to midnight
The familiar date selected for a particular location.
One tick on the Moon’s clock
Its boundary follows the continuously changing Moon–Sun angle.
The tithi at sunrise
One common convention names the day from the tithi present at local sunrise.
A tithi can sometimes fall between two sunrises or extend across two of them. Special kinds of tithi →
A named observance may check the tithi at sunrise, moonrise, or another part of the day. Six controlling times →
Vāra follows the independent seven-day weekday cycle. When tithi and vāra meet →