Season Episodes Originally aired Nielsen ratings First aired Last aired Rank Average viewership (in millions) 23 October 7, 2014 (2014 - 10 - 07) May 19, 2015 (2015 - 05 - 19) 118 4.62 23 October 6, 2015 (2015 - 10 - 06) May 24, 2016 (2016 - 05 - 24) 112 4.25 23 October 4, 2016 (2016 - 10 - 04) May 23, 2017 (2017 - 05 - 23) 120 3.50 23 October 10, 2017 (2017 - 10 - 10) May 22, 2018 (2018 - 05 - 22) 151 3.04 5 22 October 9, 2018 (2018 - 10 - 09) TBA TBA TBA
when did the last episode of the flash air
May 22, 2018