What is a Tithi?
A tithi is a moon day in the Hindu calendar. It is the time the Moon takes to move a little further ahead of the Sun - about 12 degrees. One moon month has 30 tithis. Hindu festivals are chosen using the tithi, not the normal English date.
How a tithi works
Picture the Moon slowly walking away from the Sun in the sky. Every time it moves 12 steps (degrees) ahead, one tithi is finished. The Moon sometimes walks faster or slower, so a tithi can be a little shorter or longer than a normal day.
The two halves of the month
For half the month the Moon grows brighter until the full moon - this is Shukla Paksha. For the other half it gets darker until the new moon - this is Krishna Paksha.
Why a tithi matters
Most Hindu festivals and lucky timings are picked by the tithi. That is why the same festival lands on a different English date each year.
Frequently Asked Questions
How many tithis are there?
There are 30 - 15 while the Moon grows brighter and 15 while it gets darker.
Why does my festival date change every year?
Because festivals follow the Moon (the tithi), not the English calendar, and the two do not line up the same way each year.
What is the difference between a tithi and a weekday?
A tithi is a moon day. A weekday is Monday, Tuesday, and so on. The panchang shows both.
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For general information and reflection only - not professional advice. Results may vary.
Updated: June 2026 · Written by Amit Shinde, TithiSeva · Calculated with Swiss Ephemeris & Lahiri Ayanamsha.