Tithi (तिथि) is the most fundamental unit of the Hindu lunar calendar. A tithi is the time taken by the Moon to gain exactly 12° on the Sun — roughly 23.6 hours on average, though it varies because of the Moon's elliptical orbit. There are 30 tithis in a complete lunar month (a synodic month): 15 in the Shukla Paksha (bright fortnight, waxing Moon) and 15 in the Krishna Paksha (dark fortnight, waning Moon). The 30th tithi of Shukla Paksha is Purnima (full moon), and the 30th tithi of Krishna Paksha is Amavasya (new moon).

Unlike the English calendar where a day is a fixed 24-hour period, a tithi is a dynamic astronomical unit. It can start and end at any time, not necessarily at midnight or sunrise. This is why the Panchang (Hindu almanac) uses the tithi active at local sunrise as the tithi for that calendar day — a system called the Udaya Tithi rule. This means two cities in different time zones or at different longitudes can have different tithis on the same English calendar date.

Tithi is one of the five elements (Pancha Angas) of the Panchang, alongside Vara (day), Nakshatra (lunar mansion), Yoga (luni-solar day), and Karana (half-tithi). Together, these five elements describe the quality and auspiciousness of any given moment. Tithi is considered the most important of the five for determining Shubh Muhurat (auspicious timings) for ceremonies, prayers, and important decisions.

The 30 Tithis and Their Significance

The 30 tithis are classified into 5 groups based on their quality:

Type	Tithis	Quality
Nanda (नंदा)	1, 6, 11	Joyful — good for starting new work, celebrations, travel
Bhadra (भद्रा)	2, 7, 12	Auspicious — favorable for all ceremonies and decisions
Jaya (जया)	3, 8, 13	Victorious — ideal for work requiring strength or confrontation
Rikta (रिक्ता)	4, 9, 14	Empty — avoid new beginnings; good for deity-specific worship
Poorna (पूर्णा)	5, 10, 15, 30	Complete — highly auspicious; Purnima is the most powerful

Shukla Paksha vs Krishna Paksha

Shukla Paksha (शुक्ल पक्ष) — the bright, waxing fortnight running from Amavasya to Purnima — is the preferred period for most auspicious activities: marriages, Griha Pravesh (housewarming), starting a business, initiating new ventures, and performing most religious ceremonies. The increasing moonlight is seen as symbolizing growth, prosperity, and divine favor.

Krishna Paksha (कृष्ण पक्ष) — the dark, waning fortnight from Purnima to Amavasya — is associated with completion, ancestor worship, and spiritual practices. Shraddha (ancestor rituals), Pitru Tarpan, and certain Tantric practices are preferentially performed in Krishna Paksha. Amavasya (the last day) is the most powerful day for ancestral rites. While major auspicious ceremonies are generally avoided, Krishna Paksha is not entirely inauspicious — many fasting observances, including Ekadashi (one of the most sacred tithis), fall in both Pakshas.

Special Tithis — Ekadashi, Purnima, and Amavasya

Ekadashi (the 11th tithi) occurs twice a month — once in Shukla Paksha and once in Krishna Paksha — making it 24 times a year. It is the most widely observed fasting tithi among Vaishnavas and is dedicated to Lord Vishnu. Fasting on Ekadashi is believed to cleanse the body and accumulate spiritual merit. Each Ekadashi has a specific name (Nirjala, Devshayani, Kartika, etc.) and its own significance.

Purnima (Poorna/full moon) is the most celebrated tithi. Major Hindu festivals fall on Purnima: Holi (Phalguna Purnima), Guru Purnima (Ashadha Purnima), Sharad Purnima (Ashwin Purnima), and Buddha Purnima (Vaishakha Purnima). Satyanarayan Puja is traditionally performed on Purnima. The full moon amplifies all energies and is considered extremely auspicious for spiritual practices.

Amavasya (new moon) is dedicated entirely to ancestor worship. Pitru Tarpan (water offerings to ancestors), Shradh, and Pind Daan are performed on Amavasya. Starting new auspicious activities is strictly avoided. Somvati Amavasya (Amavasya falling on Monday) is particularly powerful for Shiva worship and has a special place in Hindu tradition.

Frequently Asked Questions

What is a Tithi?

Tithi (तिथि) is a lunar day in the Hindu calendar — the time it takes for the Moon to move 12° ahead of the Sun. There are 30 tithis in a lunar month: 15 in the bright fortnight (Shukla Paksha, from new moon to full moon) and 15 in the dark fortnight (Krishna Paksha, from full moon to new moon). Tithis are the most fundamental unit of the Hindu Panchang.

What is Aaj Ki Tithi?

Aaj Ki Tithi (आज की तिथि) means 'today's tithi' — the current lunar day in the Hindu calendar. It changes daily (and sometimes within a day, since tithis are based on the Moon's exact position). Knowing today's tithi helps determine auspicious timings for ceremonies, fasting, and daily activities.

How many tithis are there and what are their names?

There are 30 tithis in total, though Amavasya (new moon) is technically the 30th. The 15 Shukla Paksha tithis are: Pratipada, Dwitiya, Tritiya, Chaturthi, Panchami, Shashthi, Saptami, Ashtami, Navami, Dashami, Ekadashi, Dwadashi, Trayodashi, Chaturdashi, and Purnima. The 15 Krishna Paksha tithis follow the same names and end with Amavasya instead of Purnima.

Which tithis are auspicious for new work?

The 5 types of tithis have different qualities: Nanda (1, 6, 11) — joyful, good for celebrations and new work. Bhadra (2, 7, 12) — stable and auspicious for all ceremonies. Jaya (3, 8, 13) — victorious, ideal for work requiring strength. Rikta (4, 9, 14) — empty/inauspicious for new beginnings but powerful for deity worship. Poorna (5, 10, 15/30) — complete and very auspicious. Avoid starting major new work on Rikta tithis (Chaturthi, Navami, Chaturdashi, Amavasya).

What is the difference between Shukla Paksha and Krishna Paksha?

Shukla Paksha (शुक्ल पक्ष) is the bright fortnight — the waxing Moon period from Amavasya (new moon) to Purnima (full moon). It is generally considered more auspicious for new beginnings, ceremonies, and positive activities. Krishna Paksha (कृष्ण पक्ष) is the dark fortnight — the waning Moon period from Purnima to Amavasya. It is associated with completion, ancestor worship, and spiritual practices.

Why does the tithi sometimes change during the day?

A tithi is not exactly 24 hours — it is the time for the Moon to travel 12° relative to the Sun, which averages about 23.6 hours. This means a tithi can start late in one day, run through the night, and end early the next day. When a tithi falls entirely within a single day (sunrise to sunrise), it is considered a Kshaya (vanished) tithi. The Panchang lists the tithi that is active at sunrise as the tithi for that day.