Understanding the Tithi (Lunar Day)
In Vedic timekeeping and Hindu astrology (Jyotisha), a Tithi is a lunar day. Unlike a standard 24-hour solar day, a Tithi varies in length from approximately 19 to 26 hours. Our Tithi Calculator uses complex astronomical algorithms to determine the exact angle between the Sun and the Moon to find the precise Tithi at any given moment.
How is it Calculated?
A Tithi is defined mathematically by the longitudinal angle between the Moon and the Sun.
Difference = (Moon Longitude - Sun Longitude)
Every time the Moon gains exactly 12 degrees on the Sun, a new Tithi begins. Because the orbit of the Moon is elliptical, the speed at which it travels varies, meaning some Tithis are shorter or longer than a standard day.
The Pakshas (Lunar Phases)
A complete lunar month consists of 30 Tithis, divided evenly into two 15-day halves called Pakshas:
- Shukla Paksha (Waxing Moon): The bright half of the month. It starts after the New Moon (Amavasya) and culminates on the 15th Tithi, the Full Moon (Purnima).
- Krishna Paksha (Waning Moon): The dark half of the month. It begins after the Full Moon and culminates on the 30th Tithi, the New Moon (Amavasya).