S45

S45 may refer to:

Aviation

 * Blériot-SPAD S.45, a French biplane airliner
 * SABCA S-45bis, a Belgian bomber
 * Short S.45, a British biplane trainer
 * Short S.45 Seaford, a British flying boat
 * Sikorsky S-45, a proposed American flying boat
 * Siletz Bay State Airport, in Lincoln County, Oregon, United States

Rail and transit

 * S45 (Berlin), a line of the Berlin S-Bahn
 * S45 (Long Island bus)
 * S45 (Vienna), a line of the Vienna S-Bahn

Other uses

 * Canon PowerShot S45, a digital camera
 * Explorer S-45 (satellite), a failed American spacecraft
 * S45: In case of accident or if you feel unwell seek medical advice immediately (show the label where possible), a safety phrase
 * INS Shankush (S45), a submarine of the Indian Navy
 * Siemens S45, a mobile phone
 * Sulfur-45, an isotope of sulfur
 * USS S-45 (SS-156), a submarine of the United States Navy
 * S45, a postcode district in Chesterfield, England
 * Saviem S45, a Savien bus model