I4

I4, I 4 or I-4 may be:
* I4 (company), a Japanese video game developer and publisher. Mostly produced games solely for Japan, including AI Shogi 3
* I4 engine, a designation for a inline-4 piston engine
* I-4 satellite
* HIJMS I-4, a WWII Imperial Japanese Navy J1 type submarine
* LB&SCR I4 class, a British
* Tupolev I-4, a 1927 Soviet aircraft

and also :
* Interstate 4, a Florida highway
* Interstate Airlines IATA airline designator
* International Information Integrity Institute (I-4), a membership-driven program established in 1986 by the Stanford Research Institute (SRI), focused on security-related issues and solutions
* i4, an integer in XML-RPC
*, I 4, a Swedish regimental designation (4th Infantry Regiment) that has been used by the following units:
** Första livgrenadjärregementet (1816–1927)
** Livgrenadjärregementet (1928–1997)