Blank Cd

I have come across a problem with one type of CDs.

I have got a pack of blank CDs, which are 99mins long and 870mb.
I have tried to copy music in a file which is 833mb long onto this blank cd using Nero, but it only gives me 800mb so i have reduce some of the music from the file.

Is there a way that lets me do this copying the full file of music onto this cd without having to take some music off.

John