What is Tithi Vridhi and Tithi Kshaya?

Tithi is an important part of panchang. Fasts and festivals are organized according to Tithi. Sometimes, we see that a festival is being celebrated on 2 days. The main reason behind this is the increase or decrease in a Tithi.

Tithi is determined with Sunrise. If there are three dates between one Sunrise and another, then out of them one date becomes kshayi or decreases. Similarly, if one date continues till two Sunrise, then that date is called ‘Vridhi’ or increasing.

These dates have a special effect on the life of the person along with every fasts and festivals. In every month, first 15 dates are called as krishna paksha and last 15 dates are called as shukla paksha. The 15th (30) date of krishna paksha is known as amavasya. On the 15th date of shukla paksha, Moon is completely visible, that’s why this date is called as Poornima. The Moon and Sun are on the same Bhogansh during Amavasya.

Why does a date increase or decrease?

Date is determined with the speed of the Sun and the Moon. In jyotish shastra, ‘Tithi Vridhi’ and ‘Tithi kshayi’ has been explained. When Sun and Moon are present together in the same ansh, then that time is called as ‘Amavasya’ and when Moon moves 12 degrees ahead of Sun then a Tithi is formed and Pratipada, Dwitiya and other dates are formed.

There is a lot of difference in the motion of the Sun and the Moon. On one hand, the Sun completes one zodiac sign in 30 days, on the other hand the Moon takes 2 and a half days to complete that. When this difference starts arising between Moon and Sun, Pratipada begins, and when this difference ends at 12 degrees, Pratipada also ends and with that Dwitiya Tithi starts.

The Vridhi and kshayi of a Tithi is mainly because of the motion of Moon. This motion of Moon keeps on increasing and decreasing. Sometimes, when Moon is at a higher speed then it can cover the distance of 12 degrees quickly and can sometimes take more time due to low speed.

How to determine ‘Tithi Vridhi’ & ‘Tithi Kshaya’?

Normally, the Bhoga Kaal of a Tithi is of 60 hours. The Vridhi and Kshayi of a Tithi is determined on the basis of sunrise. If a Tithi is beginning before sunrise, and remains till next sunrise then this situation is called as ‘Tithi Vridhi’.

For example - If on a Sunday, the time of sunrise is 06:32 am, and on that day Panchami Tithi begins at 06:15 am before sunrise, and continues till 07:53 am on Monday, the sunrise on Monday scheduled at 06:31 am and Shashthi Tithi begins after that. Thus, on both Sunday and Monday during sunrise panchami Tithi is is considered as ‘Tithi Vridhi’. The total duration of Panchami Tithi is 25h 36m, which is on an average more than 60 Ghati or 24 hours. Due to this reason the Tithi increases.

Opposite to this situation, when a Tithi starts after sunrise and ends after sunrise on the next day then this is known as ‘Kshaya’ or decrease, which we call as ‘Tithi Kshaya’. Example of ‘Tithi Kshaya’ - If on Friday sunrises at 07:12, and Ekadashi Tithi ends at 07:36 after sunrise the next day ushering in the Dwadashi Tithi. Now this Dwadashi Tithi will remain only for 30:26 minutes ie. till 06:26 am, and after that ‘Trayodashi Tithi’ starts. If sunrise takes place at 07:13, then it means that no sunrise has taken place in ‘Dwadashi Tithi’. As a result it was ‘Ekadashi Tithi’ during the time of sunrise on Friday it and on Saturday during sunrise it was ‘Trayodashi Tithi’, due to this ‘Dwadashi Tithi’ was compromised leading to its Kshaya.

Main Names of Tithis

Every Tithi is known by a different name. They also have effects based on these names. These are the names of Tithis - Nanda, Bhadra, Jaya, Rikta and Poorna. 1-6-11 is known as Nanda Tithi, this Tithi depicts happiness. 2-7-12 is known as Bhadra Tithi, which reflects growth. 3-8-13 is known as Jaya Tithi, which depicts victory. 4-9-14 is known as Rikta Tithi, which is not considered favourable. 5-10-15 comes under Poorna Tithi, which depicts auspiciousness.