According to the FIDE Rating Regulations, it depends on the player ratings:
1.1 For a game to be rated each player must have the following minimum periods in which to complete all the moves, assuming the game lasts 60 moves.
Where at least one of the players in the game has a rating 2200 or higher, each player must have a minimum of 120 minutes.
Where at least one of the players in the game has a rating 1600 or higher, each player must have a minimum of 90 minutes.
Where both of the players in the game are rated below 1600, each player must have a minimum of 60 minutes.
1.2 Where a certain number of moves is specified in the first time control, it shall be 40 moves.