There is no offical football pitch size
Football (soccer) pitches are all different sizes. There are only minimum and maximum lengths:
Min length: 90m — Max length: 120m
Min width: 45m — Max width: 90m
The length must be longer than the width. So theoretically you could have a pitch that’s 90m x 89m.
One of the longest pitches is Hull’s KC Stadium Hull City AFC at 114 metres
http://www.football-stadiums.co.uk/articles/are-all-football-pitches-the-same-size/