A standard Counter-Strike: Global Offensive half contains a maximum of 15 rounds.
In the usual competitive format, teams play 15 rounds on one side before switching roles. One team attacks as terrorists and the other defends as counter-terrorists, then they change sides for the second half. The first team to reach 16 round wins takes the match, unless the score reaches 15–15.
This structure produces a regulation maximum of 30 rounds. A tied 15–15 score is a draw in formats that permit draws, while tournament matches may use overtime rules to determine a winner. Overtime commonly adds shorter sets of rounds rather than simply extending the normal half indefinitely.
The 15-round half rule belongs to the traditional Global Offensive competitive format. Counter-Strike 2 introduced Premier and tournament configurations with their own details, so players should check the competition’s rules. The answer is not 16: 16 is the normal winning target, not the maximum length of one half.