Usually its around 3-8 minutes. Im usually disappointed,cuz i worry im not satisfying my gf, but she says i am....sooo i'll belive her. If im drunk i can go forever, also comin down from dxm i can go forever. If i jack off once or twice before we do it, then i can go like 15-20 minutes.
Oh and jacking off i can be done in like a minute.