3X or 3-X may refer to:
Computing Windows 3.x ArcView 3.x Windows NT 3.x IBM System/3X
Music 3X Krazy, American hip-hop group Yeah 3x, single by Chris Brown Look 3X; see Look Look Look
Transport 3X, IATA code for Japan Air Commuter Alberta Highway 3X; see List of Alberta provincial highways Saab 9-3X, a model of Saab 9-3 SEV-3X, a model of Seversky SEV-3
Other uses Three times or thrice 3X or XXX, a reference to the municipal flag of Amsterdam* HTV-3X, see DARPA Falcon Project
See also X3 (disambiguation) XXX (disambiguation)