Tithi (Sanskrit: तिथि) is the Hindu concept of the lunar day — the primary time unit in Hindu ritual calendar. Each lunar month has 30 tithis divided into two fortnights (paksha): Shukla Paksha (bright, waxing moon) and Krishna Paksha (dark, waning moon). Understanding tithis is essential for observing Ekadashi, Purnima, Amavasya and festival dates.

The 30 Tithis

  • Shukla Paksha (waxing) — from Amavasya to Purnima: Pratipada, Dwitiya, Tritiya, Chaturthi, Panchami, Shashti, Saptami, Ashtami, Navami, Dashami, Ekadashi, Dwadashi, Trayodashi, Chaturdashi, Purnima
  • Krishna Paksha (waning) — from Purnima to Amavasya: same 15 names, ending in Amavasya (new moon)

Important Tithis

  • Amavasya — new moon; special for ancestral rituals (shraddha, tarpana)
  • Purnima — full moon; festivals, Lakshmi worship, Satyanarayan puja
  • Ekadashi — 11th; Vishnu fasting, twice monthly
  • Chaturthi — 4th; Ganesha day
  • Ashtami — 8th; Devi + Krishna days
  • Trayodashi — 13th; Pradosh (Shiva)
  • Chaturdashi — 14th; Shivaratri especially Krishna Paksha

Tithi Calculation

Each tithi corresponds to 12° of angular separation between sun and moon. Because the moon moves faster than the sun, tithis have variable durations (roughly 22-25 hours). A tithi can be 'lost' or 'extra' depending on when sunrise falls.

Which Tithi Applies?

The tithi 'in force' at sunrise is generally the tithi observed for that day, though some observances (like Ekadashi) may follow specific rules for how a spanning tithi is counted.

Advertisement

For Daily Practice

Modern panchanga apps calculate exact tithi timings for any location. Traditional practice: consult family purohit for major observances; use apps for daily awareness; know your family's traditional practices for spanning-tithi rules.

  • Hindu Glossary A-Z: Complete Dictionary
  • Sanatana Dharma Foundations
  • Puja Encyclopedia