How many Navratras are in an year?

Navratras are very popular in Indian Hindu culture. Two most famous Navratras one in Chaitra (Usually fall in March-April) & Ashwin (usually fall in September-October) are widely know and celebrated by Public in general. However there are two more Navaratras which Fall in the month of Ashadh (usually June-July) & Magha(usually fall in Jan-Feb) months of Indian lunar calendar.

Navaratris are considered a very powerful time for performing auspicious deeds and austerities (Sadhanas). People keep bird feeders in the balconies or give alms to poor and donate generously during this period to gain mulitifold merit. Many people leave alcohol and no veg food during Navaratras. Navratrs have a tremendous impact on our thinking and this has been ingrained deeply in Indian psyche.

Gupta Navratras are generally not discussed in common public. There is a general perception that it is for Sadhus(Ascetics) & Sanyasis. This is due to the fact that these Navratrs are very powerful for sadhana and there are no festivities , celebrations in public . This helped the ascetics to perform their sadhanas peacefully and they had easier access to the auspicious and holy temples.

All Navratras start in Shulkla Paksha( Bright fortnight) on Pratipada ( The First day) and last for nine days as per lunar cycle. Please note at times a day could be lesser than 9 solar days (called Tithi Khsaya) or could be a day more ( Called Tithi Vriddhi).

In 2016 Navratra Dates are as follows:
Chaitra Navratra : 1 April 2016
Ashadh Navratra : 21 June 2016
Ahsvin Navratra : 1 October 2016
Magh Navratra : 26 January 2016

In 2017 Navratra Dates are as follows:

Chaitra Navratra : 28 March 2017
Ashadh Navratra : 24 June 2017
Ahsvin Navratra : 21 September 2017
Magh Navratra : 28 January 2017