23 hours bluray

50gb bluray are supposed to hold 23 hours of standard definition video. which means 25 gb should be 11 hours and some change. how do I burn 9 1/2 hours of video with menu to a bluray. this is a combination of about 10 years of home movies from my parents old 35 mm camera. i have converted it to digital format and have put it through adobe premier and now though encore but cant down size it to fit onto the 25gb disc. I know dvd shrink would work with dvd but not bluray anyone know of a solution, :confused