How many Ekadashi are there in a year?
Not only Ekadashi but also all tithis (other than Purnima (full moon day) and Amavasya (no moon day) which occur only once in a month) come twice in a month i.e one in Krishna Paksha and one in Shukla Paksha. Also, There is a concept of Adhika Maasa (extra month) which occurs about every 32.5 months to keep the lunar (a lunar year contains only 354.36 days) and solar calendars aligned.
So there are 24 Ekadashi fasting days in a normal year
- Utpanna Ekadashi - Margashirsha, Krishna Ekadashi
- Mokshada Ekadashi - Margashirsha, Shukla Ekadashi
- Saphala Ekadashi - Pausha, Krishna Ekadashi
- Pausha Putrada Ekadashi - Pausha, Shukla Ekadashi
- Shattila Ekadashi - Magha, Krishna Ekadashi
- Jaya Ekadashi - Magha, Shukla Ekadashi
- Vijaya Ekadashi - Phalguna, Krishna Ekadashi
- Amalaki Ekadashi - Phalguna, Shukla Ekadashi
- Papmochani Ekadashi - Chaitra, Krishna Ekadashi
- Kamada Ekadashi - Chaitra, Shukla Ekadashi
- Varuthini Ekadashi - Vaishakha, Krishna Ekadashi
- Mohini Ekadashi - Vaishakha, Shukla Ekadashi
- Apara Ekadashi - Jyeshtha, Krishna Ekadashi
- Nirjala / Pandava / Bhimseni / Bhima Ekadashi - Jyeshtha, Shukla Ekadashi
- Yogini Ekadashi - Ashadha, Krishna Ekadashi
- Devshayani / Padma / Ashadi/ Hari Shayani Ekadashi - Ashadha, Shukla Ekadashi
- Kamika Ekadashi - Shravana, Krishna Ekadashi
- Shravana Putrada / Pavitropana Ekadashi / Pavitra Ekadashi - Shravana, Shukla Ekadashi
- Aja Ekadashi - Bhadrapada, Krishna Ekadashi
- Parsva / Parivartini Ekadashi - Bhadrapada, Shukla Ekadashi
- Indira Ekadashi - Ashwina, Krishna Ekadashi
- Papankusha Ekadashi - Ashwina, Shukla Ekadashi
- Rama Ekadashi - Kartika, Krishna Ekadashi
- Prabodhini / Dev Uthani / Devutthana Ekadashi - Kartika, Shukla Ekadashi
There are 2 extra Ekadahsis in Adhika Maasa. Hence, there would be 26 Ekadashi fasting days in a year which has Adhika Masa:
How many days after one another Ekadashi comes? and why?
Generally 15 days but not necessarily. As mentioned above Ekadashi re-occurs after 15 tithis but there is no fixed duration for a tithi.
Does each one different from each other? why is it different?
Each one is associated with some story of Lord Vishnu. For example, DevShayani Ekadashi and DevUthani Ekadashi are completely different.
Padma Purana: Uttara-Khanda has a dedicated chapter on each Ekadashi:
Does the sequence of Ekadashi remain same for each year? Why do they come in the same sequence?
Like we have Jan, Feb... similarly we have Chaitra, Vaisakha...
So the sequence remains the same.
Is there any Ekadashi, which is most important hence most people follow it?
This depends on opinion, belief and geographical location. In Narada Purana:
Sanatkumar says: "O Narada! A fast on Ekadashi (eleventh day) in both the phases of a month pleases Sri Hari and fulfills all the desires".
As per PADMA-PURANA : UTTARAKHANDA : Chapter 51. Nirjala Ekadasi, sage Vyasa advised Bhima to observe single Nirjala Ekadasi fasting to compensate for not observing all Ekadashi fasting in a year. More details in
Why Nirjala Ekadashi is also known as Bhima Ekadashi? post.
In my geographical location, few people give more importance to Nirjala, DevShayani, Parivartini (Parsva) and DevUthani Ekadashis.
Difference between Purnimanta and Amanta
Story of king Ambarīṣa : SB 9.4 and SB 9.5