Each fortnight has fifteen tithis, and they fall into five classes in a repeating cycle: Nanda (1, 6, 11), Bhadra (2, 7, 12), Jaya (3, 8, 13), Rikta (4, 9, 14) and Purna (5, 10, 15, where the 15th is the full moon or the new moon). The cycle is the same in the bright and the dark half. Kalaprakasika (1917, pp. 183–184) lists the classes and says Rikta, the “empty” class, should be avoided for new work.
☕ Five classes, by place in the fortnight
A tithi is a lunar day, and a fortnight has fifteen of them. Count them in fives and you have the five classes: the 1st, 6th and 11th tithi are Nanda (“joy”); the 2nd, 7th and 12th Bhadra (“good”); the 3rd, 8th and 13th Jaya (“victory”); the 4th, 9th and 14th Rikta (“empty”); and the 5th, 10th and the full or new moon Purna (“full”). The same cycle runs in the dark half, so the dark Ekadashi is Nanda just as the bright one is.
Kalaprakasika (1917, pp. 183–184) gives the classes in its chapter on adverse yogas, and adds one line about them: “Paksha-chidhra and Rikthai, should be avoided.” That is why Rikta is the class the muhurtha books set aside for starting something new. Sanjay Rath's Crux of Vedic Astrology (pp. 10–11) gives the same five classes in both halves, for use in a star chart, and grades none of them. Muhurta Chintamani prints the same cycle on its plate (p. 8). The books belong to one tradition, so this shows how the table was handed down, not three separate proofs of it.
The day score on the home screen weighs the class of the day's tithi. It rates Purna highest and Rikta lowest of the five. Four tithis get their own weight instead of their class's: Ashtami of both halves, Pournami, Amavasai. Those numbers are the app's own; the books only name the classes and set Rikta aside.
Nava Panchangam's day score uses this rule. The weight the score gives it is the app's own choice; the books give the rule, not a number.
The five classes at a glance
- Nanda (joy): Prathamai, Shasthi, Ekadashi
- Bhadra (good): Dwitiyai, Saptami, Dwadashi
- Jaya (victory): Tritiyai, Ashtami, Trayodashi
- Rikta (empty): Chaturthi, Navami, Chaturdashi
- Purna (full): Panchami, Dasami, Pournami
- The dark half repeats the same five classes.
- The new moon is Purna, as the full moon is.
- Kalaprakasika sets Rikta aside for new work.
- The day score rates Purna highest and Rikta lowest.
Frequently Asked Questions
Which tithis are Rikta?
The 4th, 9th and 14th of each fortnight: Chaturthi, Navami, Chaturdashi, in the bright half and again in the dark half.
Why do the books set Rikta aside?
Kalaprakasika (p. 184) says plainly that Rikta should be avoided, together with the Paksha-chidra tithis. It gives no reason beyond the name: rikta means “empty”. The tradition sets such a day aside for starting something new.
Is the new moon in the Purna class?
Yes. Kalaprakasika (p. 184) puts both the full moon and the new moon in Purna, and the app does the same. The day score still gives the new moon its own weight, lower than Purna's.
Does the class alone decide a good time?
No. The class is one fact about one of the five limbs of the day. A muhurtha also looks at the weekday, the star, the yoga and the karana, and the books give each occasion its own list of tithis.
From the source
All thirty tithis by class, and where the classes are used next.
🌓 All thirty tithis, class by class
As Kalaprakasika (1917, pp. 183–184) lists them, with the tithi names the app uses. The 15th tithi is the full moon in the bright half and the new moon in the dark half.
| Class | Place in the fortnight | Bright half | Dark half |
|---|---|---|---|
| Nanda (joy) | 1, 6, 11 | Prathamai, Shasthi, Ekadashi | Prathamai, Shasthi, Ekadashi |
| Bhadra (good) | 2, 7, 12 | Dwitiyai, Saptami, Dwadashi | Dwitiyai, Saptami, Dwadashi |
| Jaya (victory) | 3, 8, 13 | Tritiyai, Ashtami, Trayodashi | Tritiyai, Ashtami, Trayodashi |
| Rikta (empty) | 4, 9, 14 | Chaturthi, Navami, Chaturdashi | Chaturthi, Navami, Chaturdashi |
| Purna (full) | 5, 10, 15 | Panchami, Dasami, Pournami | Panchami, Dasami, Amavasai |
🧭 Where the classes are used
The classes are a building block. Muhurta Chintamani pairs them with the weekday to name yogas such as Siddha and Amrita; see weekday and tithi-class yogas. Rikta also overlaps a wider list the books avoid, the Paksha-chidra tithis; see tithi lords and chhidra tithis. New to tithis? Start with what a tithi is.