I am going with 60, but a few people seem to think it's 48. The main reason I ask is that the pitcher I am using at tomorrows dunk is full up to the edge at 60oz and very hard to get a good tilt on before is starts to pour out.
In the late 80s and early 90s, the pitchers at the Chicken were 60 oz. They would actually hold 64 oz to the rim, but properly filled, they held 60 oz of beer.
I've seen bars now that sell what they call "pitchers" which look to be much smaller than that.