 Disc capacities are 25 GB for single-layer discs, 50 GB for double-layer discs, 100 GB ("XL") for triple-layer, and 128 GB for quadruple-layer (in BD-R only).The minimum speed at which a Blu-ray Disc can be written is 36 megabits (4.5 megabytes) per second., there are five versions of Blu-ray Disc Recordable Erasable (BD-RE) and four versions of Blu-ray Disc Recordable (BD-R).