<P> In all levels of Canadian football , the offensive team must run a play within 20 seconds of the referee whistling the play in ; in amateur American football , teams have 25 seconds from the time the ball is declared ready for play . In the NFL , teams have 40 seconds timed from the end of the previous down . Before 2008 , in college football , the play clock was 25 seconds after the ball was set , but the clock was not stopped for the ball to be set unless the previous play resulted in a stoppage of the clock . Now , the same intervals as the NFL are used , with minor differences for the final two minutes of each half . Various professional leagues have used their own standards ; the XFL , for instance , used a 35 - second play clock to encourage faster play . </P>
<P> In all levels of Canadian football , the offensive team must run a play within 20 seconds of the referee whistling the play in ; in amateur American football , teams have 25 seconds from the time the ball is declared ready for play . In the NFL , teams have 40 seconds timed from the end of the previous down . Before 2008 , in college football , the play clock was 25 seconds after the ball was set , but the clock was not stopped for the ball to be set unless the previous play resulted in a stoppage of the clock . Now , the same intervals as the NFL are used , with minor differences for the final two minutes of each half . Various professional leagues have used their own standards ; the XFL , for instance , used a 35 - second play clock to encourage faster play . </P>
when does the playclock start in the nfl
when does the playclock start in the nfl
the end of the previous down
the end of the previous down