what are the quarters in a calendar year
First quarter , Q1 : 1 January -- 31 March ( 90 days or 91 days in leap years ) </Li> <Li> Second quarter , Q2 : 1 April -- 30 June ( 91 days ) </Li> <Li> Third quarter , Q3 : 1 July -- 30 September ( 92 days ) </Li> <Li> Fourth quarter , Q4 : 1 October -- 31 December ( 92 days )