How many minutes of commercials in 30 minute tv show?

In the US there are approximately eight or 8-1/2 minutes of commercials per half hour of Broadcast Television. On cable there are about 10 full minutes of commercials which is why syndicated versions of television shows are edited to remove at least 1-1/2 to 2 minutes of the show to fit in the cable channel's timeslot. Pay cable shows have no commercials and can be anywhere from 25 minutes to 29 minutes in length.

In the UK on ITV and other commercial networks there are 6 to 7-1/2 minutes of commercials per half hour, but the BBC only shows commercials for their own shows at the end of a program if there is room, so a half-hour show there can run up to 29-1/2 minutes with no commercials at all.