I have been typically putting 2 tapes per one BD-R (2 hours HDV @ 1080x1440). I guess I chose this because DVD's always held that amount in SD video. I did 11 projects this size on the last one I had 40 minutes of video on one last tape - I decided to add it on and see what would happen. It all fit!
After the brn I looked at the back of the disc, it looked like it could still take more.
How much HDV (1080 x 1440) can a 25gb BD-R hold at Premiere's default settings?
A BluRay will hold just a little over two and a half hours of hi-def video before it will need to decrease the bitrate of your file to squeeze it all in.
It depends on what kind on encoding mechanism you are using as well. If you are using H264 in which encoding speed is lesser than you would be able to put more data.However if you use MPEG2 then little less.
On an average it can take around 2- 2.5 hrs of data