From the FA's site:
http://www.thefa.com/football-rules...laws/football-11-11/law-1---the-field-of-play
http://www.thefa.com/football-rules...laws/football-11-11/law-1---the-field-of-play
Dimensions
The touchline must be longer than the goal-line.
Length (touchline):
minimum 90m (100yds)
maximum 120m (130yds)
Length (goal-line):
minimum 45m (50yds)
maximum 90m (100yds)