Tithi (తిథి) is one of the most fundamental concepts in the Hindu Panchangam. It represents the lunar day, defined by the angular distance between the Sun and the Moon. Each tithi corresponds to a 12-degree increment in the Moon's elongation from the Sun, making it a precise astronomical measurement that has been tracked for millennia.
How Tithis Are Calculated
The Moon moves approximately 12 to 13 degrees per day relative to the Sun. Each time the Moon moves 12 degrees away from the Sun (measured along the ecliptic), a new tithi begins. Since the Moon's orbital speed is not constant — it moves faster at perigee and slower at apogee — tithis are not of equal duration. A tithi can last anywhere from about 19 hours to over 26 hours.
The 30 Tithis of a Lunar Month
A complete lunar month (chandramasa) has 30 tithis divided into two fortnights:
Shukla Paksha (శుక్ల పక్షం) — the bright half, from new moon to full moon: Pratipada (1), Dwitiya (2), Tritiya (3), Chaturthi (4), Panchami (5), Shashthi (6), Saptami (7), Ashtami (8), Navami (9), Dashami (10), Ekadashi (11), Dwadashi (12), Trayodashi (13), Chaturdashi (14), and Purnima (15/full moon).
Krishna Paksha (కృష్ణ పక్షం) — the dark half, from full moon to new moon: The same sequence from Pratipada to Chaturdashi, ending with Amavasya (30/new moon).
Significance of Specific Tithis
Each tithi has a presiding deity and special significance
Pratipada (పాడ్యమి): New beginnings, ruled by Agni. Good for starting new projects. Chaturthi (చవితి): Sacred to Ganesha. Vinayaka Chaturthi and Sankashti Chaturthi are observed on this tithi. Panchami (పంచమి): Sacred to Nagas and Saraswati. Vasant Panchami and Nag Panchami fall on this tithi. Shashthi (షష్ఠి): Sacred to Kartikeya (Subramanya). Subramanya Shashthi is observed. Ashtami (అష్టమి): Sacred to Shiva and Durga. Janmashtami and Durga Ashtami are important. Ekadashi (ఏకాదశి): Sacred to Vishnu. Fasting on Ekadashi is one of the most widely observed vratas. Trayodashi (త్రయోదశి): Pradosh Vrat is observed on this tithi for worshipping Shiva. Chaturdashi (చతుర్దశి): Maha Shivaratri falls on Krishna Chaturdashi. Purnima (పూర్ణిమ): Full moon — considered very auspicious. Many festivals like Guru Purnima, Kartika Purnima fall on this day. Amavasya (అమావాస్య): New moon — sacred for Pitru Tarpana (ancestor worship).
Tithi and Festival Determination
Most Hindu festivals are determined by tithis rather than the Gregorian calendar, which is why festival dates "move" every year in the Western calendar. For example, Diwali always falls on Kartika Krishna Amavasya, Vinayaka Chavithi on Bhadrapada Shukla Chaturthi, and Ugadi on Chaitra Shukla Pratipada.
The rule for determining festival dates usually depends on which tithi is in effect at sunrise or at a specific time. Different traditions may follow slightly different rules, which is why festival dates sometimes vary by a day between regions.
Tithi Dosha
Inauspicious Tithis
Certain tithis are generally considered inauspicious for starting new ventures
Rikta tithis (Chaturthi, Navami, Chaturdashi) are considered empty or depleted. Amavasya is avoided for auspicious events. Ashtami combined with certain nakshatras can be challenging. However, these tithis have their own special significance for specific types of worship and spiritual practices.
Understanding tithis deepens your connection to the rhythmic dance of Sun and Moon that governs much of Hindu religious life. Whether determining a festival date or selecting a muhurtam, tithi knowledge is essential for anyone following the Vedic calendar tradition.
Nitya Panchangam Editorial
Vedic Calendar & Astrology Editors
The Nitya Panchangam editorial team researches and writes on Vedic astronomy, traditional Panchangam calculations, Hindu festivals, and Muhurtam. All articles are reviewed against classical references including Surya Siddhanta, Muhurta Chintamani, and modern astronomical data (Lahiri Ayanamsa).
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