What Is Tithi? Understanding the 30 Lunar Dates

A Tithi is the basic unit of the Hindu lunar calendar — but it isn't a day in the way we normally mean. A Tithi is defined purely by angle: it's the time it takes for the angular gap between the Moon and the Sun, as seen from Earth, to increase by exactly 12 degrees.

Why a Tithi isn't 24 hours

The Moon's speed around the Earth isn't constant — it moves faster near perigee (closest to Earth) and slower near apogee (furthest away). Because a Tithi is defined by angle, not by clock time, this means a single Tithi can last anywhere from about 19 hours to about 26 hours. Two consequences follow directly from this:

• A Tithi can start and end within a single calendar day — sometimes a short Tithi is "skipped" from the calendar's perspective, called a Kshaya Tithi.
• A Tithi can span across a sunrise and therefore appear to "belong to" two consecutive calendar days, called an Adhika Tithi in some contexts.

This is also the reason a specific festival's Tithi (say, Kartika Amavasya for Diwali) can occasionally be observed on slightly different Gregorian dates in different cities — the Tithi's exact start/end moment can fall on either side of local sunrise.

The 30 Tithi names

A lunar month has exactly 30 Tithis, split into two Pakshas (fortnights) of 15 each:

#	Name
1	Pratipada
2	Dwitiya
3	Tritiya
4	Chaturthi
5	Panchami
6	Shashthi
7	Saptami
8	Ashtami
9	Navami
10	Dashami
11	Ekadashi
12	Dwadashi
13	Trayodashi
14	Chaturdashi
15	Purnima (Shukla) / Amavasya (Krishna)

The same 14 names repeat in both Pakshas; only the 15th Tithi differs — Purnima (full moon) ends Shukla Paksha, Amavasya (new moon) ends Krishna Paksha.

Why Tithi matters

Almost every Hindu festival is defined by a specific Tithi in a specific month, not by a fixed Gregorian date. Diwali is Kartika Amavasya. Holi is Phalguna Purnima. Ekadashi — the 11th Tithi — is significant enough to have its own fasting tradition observed twice every month; see What Is Ekadashi? and the full 2027 Ekadashi calendar.

See today's Tithi

Check today's Tithi directly, our broader live Panchanga for the current Tithi alongside all five elements, or explore the full Tithi reference for how each one relates to daily practice.

Kshaya Tithi: when a Tithi seems to disappear

Because Tithi length varies with the Moon's orbital speed, occasionally a Tithi is short enough (closer to the 19-hour minimum) that it begins and ends entirely within a single sunrise-to-sunrise day — meaning that Tithi never gets its "own" calendar day and appears to be skipped entirely from a day-by-day listing. This is called a Kshaya Tithi ("diminished Tithi"), and it's a well-understood, expected feature of the system rather than an error in any particular Panchang. The opposite case — a Tithi so long (closer to 26 hours) that it spans parts of two different sunrise-to-sunrise days and appears to repeat — is sometimes called a Vriddhi ("increased") Tithi.

A simple calculation walkthrough

Suppose at a given moment the Moon's ecliptic longitude is 150° and the Sun's is 120°. The angular gap is 30°. Dividing by 12° per Tithi gives 2.5, meaning we're partway through the 3rd Tithi (each Tithi covering one 12° band: 0°–12° is the 1st, 12°–24° is the 2nd, 24°–36° is the 3rd, and so on). If this is within the first 15 Tithis (0°–180° gap), we're in Shukla Paksha, so this would be Shukla Tritiya — the 3rd day of the waxing fortnight. The same arithmetic, extended to the full 0°–360° range, is what a Panchanga calculator performs continuously to track which Tithi is current at any moment.

Why Tithi calculations matter beyond festival dates

Tithi isn't only used for naming festival days — it's also central to Muhurta (auspicious timing selection), where specific Tithis are traditionally considered favourable or unfavourable for particular activities (starting a journey, a wedding, a new venture). See our Muhurta guide for how Tithi feeds into that broader timing-selection system.

Tithi names in everyday conversation

Several Tithi names have become common vocabulary well beyond calendar contexts — Purnima (full moon) and Amavasya (new moon) are widely recognised terms in India even among people who don't otherwise track the Hindu calendar closely, roughly the way "full moon" and "new moon" function in everyday English. Ekadashi, similarly, is recognised primarily through its associated fasting practice rather than as an abstract "11th lunar day" — see our Ekadashi explainer for that specific tradition.

How this connects to the wider Panchanga

Tithi is one of five elements that together make up a complete Panchanga reading for any given day. It's calculated independently of the other four (Nakshatra, Yoga, Karana, Vara), which is why a specific Tithi doesn't always coincide with the same Nakshatra or Yoga from month to month. See our full Panchanga guide for how all five fit together, and how Hindu calendar dates are calculated for the complete astronomical picture.