2018 Purnima Fasting Days
Purnima Full Moon
Purnima fasting might be observed either on Purnima day or on one day before Purnima day i.e. on Chaturdashi day depending on starting time of Purnima Tithi on previous day.
Purnima fasting on Chaturdashi occurs only when Purnima starts during Madhyahna period on previous day. It is believed that if Chaturdashi prevails beyond Madhyahna then it pollutes Purnima Tithi and this Chaturdashi day should not be considered for Purnima fasting even if Purnima prevails during evening. There are no two opinions on this rule and DrikPanchang.com lists Purnima fasting days according to this rule.