Ekadasi is an auspicious day dedicated to Lord Vishnu on the eleventh day of every lunar fortnight in traditional Hindu calendar. Ekadasi 2012 — 2013 dates based on Hindu Lunar Calendar. Vaikunta Ekadasi 2012 is on December 23. Fasting on Ekadashi is considered highly auspicious and is believed to help in redemption of sins and in attaining Moksha. Below are the Ekadasi dates in 2012 — 2013.
The Ekadasi dates are based on Indian Standard Time (IST).

Ekadasi 2012
June 15, 2012 – Yogini Ekadasi
June 30, 2012 – Devshayani Ekadashi – Sayana Ekadasi — Ashadi Ekadasi
July 14, 2012 – Kamika Ekadasi
July 29, 2012 — Pavitra Ekadasi – Putrada Ekadashi
August 13, 2012 – Aja Ekadasi – Annada Ekadashi
August 27, 2012 — Padmini Ekadasi — Adika Masa Ekadasi
September 12, 2012 — Kamla Ekadasi — Adika Masa Ekadasi
October 11, 2012 – Indira Ekadasi
October 25, 2012 — Pasankusa Ekadashi
November 10, 2012 – Rama Ekadasi
November 24, 2012 – Prabodini Ekadasi – Uttahana Ekadashi
December 9, 2012 – Uttpatti Ekadashi (Smarta)
December 10, 2012 — Uttpatti Ekadasi (Bhagavat)
December 23, 2012 – Mokshada Ekadasi — Vaikunta Ekadasi
December 24, 2012 — Mokshada Ekadasi (Bhagavat only for some communities)
Ekadasi 2013
January 8, 2013 — Saphala Ekadasi
January 22, 2013 – Putrada Ekadasi
February 21, 2013 — Jaya Ekadasi — Bhoumi and Bheeshma Ekadasi
March 8, 2013 – Vijaya Ekadashi
March 23, 2013 – Amalaki Ekadasi – Amalki Ekadashi
April 6, 2013 – Papmochani Ekadasi

May 5, 2013 – Varuthini Ekadashi
May 21, 2013 – Mohini Ekadasi

June 4, 2013 – Apara Ekadashi
June 19, 2013 – Bhim Ekadasi – Bhima Nirjala Ekadasi
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<Source — http://www.hindu-blog.com/2009/11/ekadasi-2010-ekadashi-calendar-fasting.html>