--- title: "Tithi in Panchang: The Lunar Day and Why It Drifts" slug: "tithi-in-panchang" canonical_url: "https://mahadasha.com/tithi-in-panchang" description: "Tithi in panchang is 12° of Moon minus Sun. Why it runs 20 to 27 hours, why some tithis vanish entirely, and what the five tithi classes mean." published_date: "2026-08-05 09:00:00" modified_date: "2026-08-05 09:00:00" author: "Pawan Acharya" keywords: "tithi in panchang, tithi meaning, tithi today, 30 tithis list, kshaya tithi, rikta tithi, shukla krishna paksha, how to calculate tithi" locale: "en" --- # Tithi in Panchang: The Lunar Day and Why It Drifts > A tithi is 12 degrees of separation between Moon and Sun. Because that takes anywhere from 20 to 27 hours, some tithis never see a sunrise at all. # Tithi in Panchang: The Lunar Day and Why It Drifts Tithi in panchang is the lunar day, and it has one definition: the Moon pulling 12° further ahead of the Sun. Thirty of those steps take the Moon from conjunction all the way round to conjunction again, which is one lunar month. So tithi one begins the instant after the new Moon, tithi fifteen ends at the full Moon, and tithi thirty ends back at the next new Moon. That is the whole rule. Everything else about tithi, including the parts that look like superstition, follows from one awkward fact about it. ## Why a tithi is not a day The Moon does not move at a constant speed. Its orbit is an ellipse, so it runs faster near perigee and slower near apogee, and the Sun is creeping forward the whole time as well. The gap between them therefore opens at a rate that varies across the month, and a 12° step takes however long it takes. Measured across 2026 against the site's own ephemeris, a tithi averaged 23 hours 35 minutes. The shortest ran 20 hours 04 minutes. The longest ran 26 hours 43 minutes. That is a spread of six and a half hours between the quickest tithi of the year and the slowest. The physical cause is worth a sentence, because it makes the variation predictable rather than mysterious. When the Moon is near perigee, the closest point of its orbit, it sweeps through the sky at its fastest and a 12° step is covered quickly. Near apogee it slows and the same step drags. The Sun contributes a smaller wobble of its own for the same reason. So the short tithis cluster around one part of the month and the long ones around the opposite part, and the pattern moves through the year as the orbit's orientation shifts. Hold that against a solar day of almost exactly 24 hours and the consequences are immediate. ## The tithi that vanishes, and the one that repeats A panchang reports the tithi running at sunrise. If a tithi is shorter than the gap between two sunrises, it can begin after one sunrise and end before the next, which means no day ever gets named after it. It is skipped. That is a *kshaya* tithi, sometimes called a lost tithi. The mirror case is a tithi long enough to be running at two consecutive sunrises, so two days in a row carry the same name. That is an *adhika* or vriddhi tithi. These are not rare events. Counting every sunrise at Delhi through 2026, 17 tithis were lost and 11 were repeated. That works out at roughly one skipped tithi every three weeks. So if you have ever seen two calendars disagree about which day a festival falls on, or wondered why a date jumped, this is very often the reason: the festival's tithi did not touch a sunrise, and the two sources resolved the gap differently. ## Shukla and Krishna, the two fortnights The thirty tithis split into two halves of fifteen. The bright half is *Shukla paksha*, from the new Moon to the full, when the illuminated part grows each night. The dark half is *Krishna paksha*, from full back to new. The paksha is doing more than labelling a fortnight. A waxing Moon is treated as stronger than a waning one, and that judgement feeds straight into chart reading, where it decides how much a placement of [the Moon in different houses](https://mahadasha.com/moon-in-different-houses) can actually deliver. Same distinction, different use. Both halves reuse the same fourteen names, Pratipada through Chaturdashi, which is why a tithi is never quoted without its paksha. The fifteenth is the exception and gets its own name in each half: Purnima at the end of the bright fortnight, Amavasya at the end of the dark one. Ask for "Ashtami" and the honest answer is a question, because Shukla Ashtami and Krishna Ashtami are two weeks apart and are used for entirely different things. ## The five classes, and why the 4th, 9th and 14th Each tithi belongs to one of five classes, and the assignment is pure arithmetic: take the tithi number within its paksha and read it modulo five. - **Nanda** (joyful): 1, 6, 11 - **Bhadra** (auspicious): 2, 7, 12 - **Jaya** (victorious): 3, 8, 13 - **Rikta** (empty): 4, 9, 14 - **Purna** (full): 5, 10, 15 Rikta means empty, and those three are the ones traditionally left alone for anything you want to last. Notice that the rule generates them rather than listing them. Because the classes cycle every five and a paksha holds fifteen tithis, the Rikta positions can only ever be the 4th, 9th and 14th, in both fortnights, in every month, forever. Six days of every lunar month, fixed by the modulus. This is also why "avoid Chaturthi, Navami and Chaturdashi" is a rule people can recite without knowing where it came from. There is nothing to memorise. Divide by five and look at the remainder. ## Why festivals move against the Gregorian calendar Almost every Hindu festival is defined as a particular tithi of a particular lunar month, not as a calendar date. Diwali is Amavasya of Kartika. Janmashtami is Krishna Ashtami of Bhadrapada. Since a lunar month runs about 29.5 days and a solar year does not divide evenly into it, those definitions drift roughly eleven days earlier each Gregorian year until an extra lunar month is inserted to pull them back. Add the kshaya problem on top and you get the disputed dates. When a festival's tithi is running at sunrise, there is no argument. When it starts at noon and ends before the next sunrise, different traditions apply different tie-breakers, and two perfectly competent almanacs print different days. ## Ekadashi, and why the eleventh gets the attention Of the thirty, one is observed far more widely than the rest. Ekadashi is the eleventh tithi of each fortnight, so it comes round twice a lunar month, roughly 24 times a year. It belongs to the Nanda class, the same group as Pratipada and Shashthi. The fasting rule is where the kshaya problem bites hardest in ordinary life. Observance is tied to Ekadashi being current at sunrise, and because tithis drift, some years produce two consecutive sunrises inside the same Ekadashi and some produce none at all. Different traditions resolve that differently, which is why two temples a few streets apart can keep the fast on different days without either being wrong. The disagreement is about the tie-breaker, not about the astronomy, and the underlying longitudes are identical in both. ## Reading tithi in panchang properly Three habits are worth having. Always take the end time with the name. A panchang saying Saptami is telling you Saptami was current at sunrise, and the end time tells you how much of the day it actually covers. On 5 August 2026 at Delhi the tithi was Krishna Saptami ending at 20:42:50, so it held for nearly fifteen hours of daylight and evening. Some days the tithi expires before breakfast. Always take the paksha with the number. Half the tithi names are ambiguous without it. And keep two questions apart that are easy to blur: which tithi *names* the day, and which tithi is *running* when you actually do the thing. The first is fixed at sunrise and is what a calendar prints. The second changes during the day. Rites that must be performed under a specific tithi care about the second, so the end time is not decoration on the panchang. It is the operative number, and ignoring it is the commonest way to observe the right day at the wrong hour. And do not treat the tithi as the whole picture. It is one of five limbs, and the karana running underneath it changes twice as often. Two karanas fill every tithi, which is covered in [karana in panchang](https://mahadasha.com/karana-in-panchang) . ## Frequently asked questions ### How is tithi in panchang calculated? Subtract the Sun's sidereal longitude from the Moon's, take the result modulo 360, and divide by 12. The integer part plus one gives the tithi number from 1 to 30. Under 15 is Shukla paksha, over 15 is Krishna. ### Why is my tithi a different length from yesterday's? Because the Moon's speed varies through its elliptical orbit. Tithis ranged from 20 hours to nearly 27 across 2026, and neighbouring tithis can differ by well over an hour. ### Why do two days show the same tithi? The tithi was long enough to be running at both sunrises, so both days are named for it. That is a vriddhi or adhika tithi, and it happened 11 times at Delhi in 2026. ### Should I use my tithi birthday or the calendar one? Traditional observance uses the tithi, which is why it lands on a different Gregorian date each year. Both are defensible. They simply answer different questions, one lunar and one solar. To see the tithi and its exact end time for any date and city, run the [panchang calculator](https://mahadasha.com/panchang-calculator) . For how the tithi sits against the other four limbs, start from [what is panchang](https://mahadasha.com/what-is-panchang) .