N45

N45 may refer to:

Transportation

 * N45 (Long Island bus)
 * BMW N45, an automobile engine
 * Kobelt Airport, in Ulster County, New York, United States
 * N-45 National Highway, in Pakistan
 * Nebraska Highway 45, in the United States

Military

 * HMS Narwhal (N45), a Grampus-class submarine of the Royal Navy sunk in 1940
 * HMS Trusty (N45), a T-class submarine of the Royal Navy scrapped in 1947