My wife is trained as a sommelier. In my understanding sommeliers generally figure five glasses to the bottle. (When we're pouring for ourselves, it's four glasses, because then we don't have to fight over who gets the extra glass.)

A bottle is 750 ml, so that's a 150-ml pour (five to the bottle) or 187.5-ml (four to the bottle). As the article says a typical glass holds about 450 ml now.