Tithiतिथि
Tithi is the lunar day — the time it takes the Moon to move 12° further from the Sun than it was at the start of the Tithi. A full lunar month has 30 Tithis.
Different Tithis are traditionally considered better or worse for different activities — some (like Panchami, Saptami, Dashami, Ekadashi, Trayodashi) are considered generally favorable for auspicious undertakings, while others (like Chaturthi, Ashtami, Navami, Chaturdashi, and Amavasya) are traditionally avoided for starting new ventures. The exact number shown (e.g. "Shukla Panchami (5)") tells you both the Tithi's name and its position (1–15) within the current Paksha.
Unlike a calendar day, a Tithi does not last a fixed 24 hours — because the Moon's speed relative to the Sun varies, a Tithi can run anywhere from about 19 to 26 hours. The Panchang shows exactly when the current Tithi ends ("till 07:03 AM") so you know precisely when it changes over.
A Tithi is not a clock-based unit — it is a relationship between the Sun and Moon. It is the time the Moon takes to move exactly 12° ahead of the Sun in the zodiac. Because the Moon moves at varying speeds, a Tithi can last anywhere from about 19 to 26 hours — sometimes two Tithis fall in a single calendar day (Vriddhi), and sometimes a Tithi is skipped entirely (Kshaya). This is why the Panchang always shows the exact end-time of the current Tithi.
The 30 Tithis split into two Pakshas of 15 each. Shukla Paksha (bright fortnight) runs from New Moon to Full Moon — the Moon is waxing. Krishna Paksha (dark fortnight) runs from Full Moon back to New Moon — the Moon is waning. Shukla Paksha is generally more auspicious for new beginnings; Krishna Paksha is associated with completion, release, and ancestral rites. The Tithi number resets at 1 at the start of each Paksha.
Classical texts classify Tithis into five groups: Nanda (1,6,11 — good for auspicious activities), Bhadra (2,7,12 — good for stable undertakings), Jaya (3,8,13 — good for overcoming obstacles), Rikta (4,9,14 — generally avoided for new starts), and Purna (5,10,15/30 — considered complete and auspicious). Amavasya and Chaturdashi carry specific restrictions for ceremonies.
Many Hindu fasts are Tithi-based: Ekadashi (11th of both Pakshas) for Vishnu devotees, Pradosh (13th) for Shiva devotees, Sankashti Chaturthi (Krishna 4th) for Ganesha devotees, Purnima for Satyanarayan Katha, and Amavasya for Pitru Tarpan. This app auto-detects all of these from the current Tithi and flags them in the Vrat section.