Tithis

Tithi is the lunar day, the stretch of time during which the angle between the Moon and the Sun grows by exactly twelve degrees. Tithi is one of the five limbs of panchanga: together with nakshatra, yoga, vara, and karana, it sets the tone of the day. A lunar month runs exactly thirty tithis — fifteen in the bright, waxing half (shukla paksha) and fifteen in the dark, waning half (krishna paksha). This section is an overview: it explains how a tithi is built, how it is measured, and how to read its number in daily practice.

What a tithi is

Tithi is not a calendar day but an astronomical interval between the Moon and the Sun. When the two luminaries meet in conjunction, the angle between them is zero — that is the new moon, Amavasya. From that moment the Moon moves, on average, 12° ahead of the Sun every 23 and a half hours, and each such twelve-degree step is one tithi. When the gap approaches one hundred eighty degrees, the luminaries stand on opposite sides of the Earth — that is Purnima, the full moon.

Because the orbits of the Moon and the Earth are neither circular nor synchronized, a tithi does not line up with a solar day: it can run shorter or longer than one. Sometimes a tithi fails to change across a single sunrise — then it is vridhi, "doubled": the same number stands in the calendar for two days running. The opposite also happens — kshaya, "lost": a tithi fails to show at sunrise and stays invisible in the calendar. Neither case is exotic: vridhi and kshaya turn up regularly in the calendar — panchanga marks them separately, and classical muhurta takes them into account.

The tithi of the day is whichever one is active at sunrise: if, say, Shukla Panchami is running at dawn, the whole day is counted as its day, even once it has changed by evening.

Dividing into pakshas

The lunar month splits into two halves. The first — from Amavasya to Purnima — is called shukla paksha, the "bright half." The Moon waxes through it, growing. The second — from Purnima to the next Amavasya — is krishna paksha, the "dark half." The Moon wanes.

So the thirty tithis are not one continuous list but two sets of fifteen. Shukla paksha opens with Shukla Pratipada and closes with Purnima; Krishna Pratipada follows the same way, and Amavasya closes the month. Every number has a counterpart in the other paksha: Dvitiya of the bright half and Dvitiya of the dark half, Chaturthi of shukla and Chaturthi of krishna — thirty articles in all, with matching numbering but a different pattern of fruits. This site follows the amanta count, where the month ends on Amavasya. In the North Indian purnimanta count, the month ends on Purnima instead, and the dark half comes first — the tithi numbers themselves don't change, only their order within the month.

By tradition, the fruits of shukla and krishna under the same number are close in tone but not identical: the bright half favors growth and new beginnings, the dark half favors finishing and winding down.

Classes of tithi

Tithis group into five classes by number, five apart. The class sets the day's general character, and this comes from classical muhurta literature (Muhurta Chintamani and related texts).

• Nanda (1, 6, 11) — "joy." Days favorable for beginnings, celebrations, pleasant matters.
• Bhadra (2, 7, 12) — "auspicious." Suited to favorable ceremonies and rites.
• Jaya (3, 8, 13) — "victory." Good for overcoming obstacles and confident starts.
• Rikta (4, 9, 14) — "empty." Tradition warns against major undertakings; these days go more often to shraddha and offerings to ancestors.
• Purna (5, 10, 15) — "full." Suited to charity, vows and austerity, rites of completeness. Amavasya (the 15th of krishna) is carved out of this class in this corpus and treated separately.

A class doesn't cancel the number, it adds to it: a specific Shukla Chaturthi is both the fourth tithi and, at the same time, a Rikta, and its effects are read as the two layers overlapping.

How to read this section

Each tithi is a separate page. The page carries a definition, its place in the system, traditional correspondences (deity, class), and the day's practical meaning. Neighboring tithis are linked through "Related terms," and through them it's convenient to move on to the day's nakshatra, vara, yoga, and karana — the other four limbs of panchanga.

When reading, keep in mind: the tithi's number is half of the month (shukla or krishna), the class is its general character, the deity is its traditional patron. The day's specific fruits are read together with the nakshatra and vara: one tithi sets the background, Tara Bala adds a personal layer, and the answer to the main question — whether the day suits your matter — comes from where the two coincide.