The same size as a Blu-Ray case.
A Blu-Ray case's closed dimensions are 170mm by 135mm with a standard width for single cases at approximately 14mm. Widths may vary depending on if it's a slimmer version or if it holds multiple discs per case.
(Originally said DVD and 190mm, but that's an Xbox 360 case).
17 cm X 13.5 cm X 13 mm