What is a Tithi?
A tithi is a lunar day — the time the Moon takes to move 12° ahead of the Sun. A tithi is not a clock date; it is set by the Moon–Sun angle. A lunar month has 30 tithis — 15 in the Shukla paksha (bright fortnight) and 15 in the Krishna paksha (dark fortnight). Most festivals and vrats are fixed on the tithi, not on the date.
A tithi is a lunar day. Your everyday calendar date is solar (set by the Sun), but a tithi is set by the angular distance between the Moon and the Sun. The time the Moon takes to move 12° ahead of the Sun is one tithi.
That is why a tithi is not fixed like a date — it grows longer or shorter with the Moon's speed. This is also the root cause of the kshaya and vriddhi tithis explained further down.
Significance
Tithi is the first limb (anga) of the panchang. The other four are the vaar (weekday), the nakshatra, the yoga, and the karana. Festivals, vrats (observances) and muhurats all hinge on the tithi, so once you understand the tithi, reading the rest of the panchang becomes easy. That is why this is the core foundational page under ‘how to read the panchang.’
The biggest difference — date vs tithi: the Gregorian date is solar and stays the same every year (e.g. January 1). A tithi is lunar and falls on a different date each year. That is why a person's ‘tithi birthday’ and ‘date birthday’ land on different days — and why the Gregorian dates of festivals and vrats shift every year.
How a tithi is set
After an amavasya (new Moon) or a purnima (full Moon), the moment the Moon has moved 12° ahead of the Sun, Pratipada (the first tithi) begins; every further 12° is the next tithi. 15 × 12° = 180° (a half circle) = one paksha.
- Amavasya (0°) → the 15 tithis of the Shukla paksha
- Purnima (180°) → the 15 tithis of the Krishna paksha
- Back to Amavasya (360°)
Because the Moon's speed keeps changing along its orbit, every tithi is not the same length — roughly 19 to 26 hours. It is not fixed at 24 hours like a date, and that is exactly what causes the kshaya and vriddhi tithis.
The 30 tithis & the two paksha
A lunar masa has 30 tithis, split across two pakshas. In both pakshas the names Pratipada through Chaturdashi are the same; the only difference is the 15th tithi and the name of the paksha.
Shukla paksha (the waxing Moon)
Pratipada · Dwitiya · Tritiya · Chaturthi · Panchami · Shashthi · Saptami · Ashtami · Navami · Dashami · Ekadashi · Dwadashi · Trayodashi · Chaturdashi · Purnima (the full Moon).
Krishna paksha (the waning Moon)
Pratipada · Dwitiya · Tritiya · Chaturthi · Panchami · Shashthi · Saptami · Ashtami · Navami · Dashami · Ekadashi · Dwadashi · Trayodashi · Chaturdashi · Amavasya (the Moon is not visible).
Purnima and Amavasya are the two special tithis — they are the joints between the two pakshas.
Maharashtra convention: the masa runs by the amanta system — the month ends at the amavasya. So the Krishna paksha falls in the second half of that same month. (This is unpacked in detail on the ‘masa / adhik maas’ page.)
Tithi & sunrise — the ‘tithi of the day’, kshaya & vriddhi
A tithi can begin or end at any clock time — not only at midnight. So the tithi running at the moment of sunrise is taken as that day's tithi.
Two January 2026 examples show why the end time matters: on 3 January 2026, Purnima ends at 15:33 in the afternoon, so it does not cover the whole clock date. On 18 January 2026, Amavasya ends at 25:21 — that is, at 01:21 on 19 January. In other words, a tithi can end at any clock time; it does not wait for midnight.
Kshaya tithi (skipped / expunged)
If a tithi begins after one sunrise and ends before the next sunrise, it touches no sunrise at all — so it is dropped. Example: the 6 January 2026 record reads ‘Krishna Tritiya / Krishna Chaturthi’ (Tritiya ends 08:09, Chaturthi ends at 30:52 — that is, 6:52 AM the next morning, 7 January, before that day's roughly 7:15 AM sunrise). The next day already has Panchami at sunrise — so Chaturthi never got a sunrise = a kshaya tithi.
Vriddhi tithi (repeated / falling on two days)
If the Moon is slow, one tithi stays running across two consecutive sunrises — so it is counted on two days. Example: Krishna Saptami falls on both 9 January 2026 (ending ahoratra = the whole day) and 10 January 2026 (ending 08:23) — Saptami is running at both sunrises → a vriddhi tithi. (In the panchang, ahoratra means ‘the tithi spans the whole day.’)
This is why the simple arithmetic ‘the Nth tithi each month = a fixed date’ does not work. Dates have to be read from panchang data; counting calendar dates alone is not enough.
The five tithi groups — Nanda, Bhadra, Jaya, Rikta, Purna
The tithis 1 to 15 within each paksha fall, in order, into five groups; the sequence repeats three times per paksha. Traditionally these groups are given different natures — but this is astrological belief that varies by family and region, so treat it as custom, not a rule.
| Group | Tithi numbers | Tithis | Nature (traditionally) |
|---|---|---|---|
| Nanda | 1, 6, 11 | Pratipada · Shashthi · Ekadashi | held to be auspicious / joyful |
| Bhadra | 2, 7, 12 | Dwitiya · Saptami · Dwadashi | held to be steady / benign |
| Jaya | 3, 8, 13 | Tritiya · Ashtami · Trayodashi | for tasks of victory / strength |
| Rikta | 4, 9, 14 | Chaturthi · Navami · Chaturdashi | avoided for auspicious beginnings |
| Purna | 5, 10, 15 | Panchami · Dashami · Purnima/Amavasya | held favourable for all tasks |
Rikta is the group of Chaturthi, Navami and Chaturdashi; these tithis are traditionally avoided for auspicious beginnings.
The Rikta Chaturthi of the Krishna paksha is itself Sankashti Chaturthi — a good example of how the tithi groups and the festivals are linked.
Date vs tithi — the reader's key question
- Date: solar, Gregorian, the same every year (e.g. January 1).
- Tithi: lunar, set by the Moon–Sun angle, on a different date each year.
Because festivals and vrats are fixed by tithi, their Gregorian dates shift every year. For example, the Shukla-paksha Ekadashi of Ashadh masa is itself Ashadhi Ekadashi — it falls on a different Gregorian date every year, but the tithi stays the same. For this reason the site stores festivals by tithi, not by date.
If you are looking for today's exact tithi, it changes daily and by place — see the today's panchang page for that. This page explains the concept; it does not show today's tithi.
Good to know
- A tithi is not fixed like a clock date — it runs roughly 19 to 26 hours.
- A kshaya tithi is skipped and a vriddhi tithi lands on two days — this is normal, not an error.
- The auspicious/inauspicious nature of the tithi groups (avoiding Rikta, etc.) varies by family and region.
- The exact start/end of today's tithi shifts by place and date → that lives on the day page; here it is only the concept.
FAQ
- What is a tithi?
- The time the Moon takes to move 12° ahead of the Sun — that is, one lunar day.
- How is a tithi measured?
- When the angular distance between the Moon and the Sun grows by 12°, the tithi advances by one.
- How many tithis are there in a month?
- Thirty — 15 in the Shukla paksha and 15 in the Krishna paksha.
- What are Shukla paksha and Krishna paksha?
- Shukla paksha is the waxing Moon (Pratipada → Purnima); Krishna paksha is the waning Moon (Pratipada → Amavasya).
- Which tithis are Purnima and Amavasya?
- The 15th tithi of the Shukla paksha is Purnima (full Moon); the 15th tithi of the Krishna paksha is Amavasya (the Moon is not visible).
- What is a kshaya tithi, and why is a tithi skipped?
- A tithi that begins after sunrise and ends before the next sunrise touches no sunrise, so it is dropped from the calendar.
- What is a vriddhi tithi, and why does one tithi fall on two days?
- When the Moon is slow, a single tithi stays running across two consecutive sunrises — so it is counted on two days.
- What is a Rikta tithi?
- Chaturthi, Navami and Chaturdashi are the Rikta tithis; traditionally they are avoided for auspicious beginnings. (Varies by tradition.)
- What is the difference between a date and a tithi?
- A date is solar and fixed every year; a tithi is lunar and shifts to a different date each year.