What are the disc capacity for DVD video discs?

DVD-5: a single-sided and single-layer disc which holds 4.7 GB of data.

DVD-9: a single-sided and double-layers disc with capacity of 8.5 GB.

DVD-7: a double-sided and single-layer disc with capacity of 9.4 GB.

DVD-18: a double-sided and double-layers disc holds 17 GB.