The size of a Blu-ray to MP4 file depends on various factors, such as the original video length, the video quality, the bit rate, and the video or audio codec used. Typically, a rough estimate for a full-length, high-quality (50MB) Blu-ray movie converted to MP4 could fall between 1-3 GB per hour of footage. DVDFab Blu-ray Ripper allows you to adjust the video and audio parameters to balance the optimal MP4 size and high quality.