Tithi: The Lunar Day

A tithi is a lunar day. It is the time taken by the Moon to move 12° further from the Sun. Because the Moon's speed varies, a tithi can last from about 19 to 26 hours.

The thirty tithis

Each half of the lunar month (paksha) has 15 tithis: Pratipada, Dwitiya, Tritiya, Chaturthi, Panchami, Shashthi, Saptami, Ashtami, Navami, Dashami, Ekadashi, Dwadashi, Trayodashi, Chaturdashi, and finally Purnima (full Moon) in the bright half or Amavasya (new Moon) in the dark half.

The tithi at sunrise

The Panchang day is named after the tithi running at sunrise. If a tithi begins after one sunrise and ends before the next, it never touches a sunrise and is called a kshaya (lost) tithi. If a tithi covers two sunrises, it is counted twice — a vriddhi (extra) tithi.

Why dates differ

Because sunrise differs from place to place, the same tithi may touch sunrise in one city but not in another. Some festivals also need the tithi at a particular time of day — midday, evening or midnight. This is why a festival can fall on different dates in different regions, and why calendars from different traditions sometimes disagree.

The groups of tithis

Tithis are also grouped by nature — Nanda (joyful), Bhadra (good), Jaya (victorious), Rikta (empty) and Purna (full). Rikta tithis (4th, 9th and 14th) are usually avoided for new beginnings.

Tithis and their deities

Each tithi has a traditional deity and use: Chaturthi for Ganesha, Panchami for the Nagas and learning, Shashthi for Skanda, Ashtami for Durga, Navami for Rama and the Goddess, Ekadashi for Vishnu, Trayodashi for Shiva (Pradosh), Chaturdashi for Shiva (Shivaratri on the dark half) and Purnima for the full Moon observances.

A worked example

A festival requires Ashtami at midnight (such as Janmashtami in many traditions). In a city, Ashtami begins at 10:30 p.m. on Monday and ends at 11:50 p.m. on Tuesday. Midnight falls within Ashtami on both nights, so traditions use further rules — such as the presence of Rohini nakshatra — to choose the day. This is why some calendars show the festival on Monday and others on Tuesday.

How long is a tithi?

Because the Moon's speed varies between about 12° and 15° a day, a tithi lasts between roughly 19 and 26 hours. When the Moon is fast, tithis are short and kshaya tithis are more likely.

Common mistakes

• Assuming one tithi per calendar day. A day can have two tithis, and a tithi can span two days.
• Using another city's Panchang. Tithi end times are the same everywhere in absolute time, but their relation to local sunrise is not.

Frequently asked questions

Is my birth tithi important? Yes. Some families celebrate birthdays by tithi rather than date, and the birth tithi is read for temperament.

What is a "nanda" tithi? The 1st, 6th and 11th tithis, considered joyful.

Key points to remember

• A tithi is 12° of the Moon's movement away from the Sun.
• The Panchang day is named by the tithi at sunrise.
• Kshaya and vriddhi tithis explain why a tithi may be skipped or repeated.
• Festival dates depend on the tithi at a specific time of day and on local sunrise.

Why do some calendars show two Ekadashi dates? Because of different rules about the previous tithi near sunrise; see Ekadashi and vrat days.