SP4

SP4 may refer to:


 * SP4, an album by Sneaker Pimps
 * Sp4 transcription factor, a human gene
 * Savoia-Pomilio SP.4, a reconnaissance and bomber aircraft built in Italy during the First World War
 * The Saint Patrick's Day Four
 * Service pack 4 in computing
 * Specialist Four (incorrectly called Specialist 4th class), a former enlisted rank of the U.S. Army, now simply Specialist
 * a model of steam toy made by British manufacturer Mamod
 * a 7.62×42mm silent pistol cartridge
 * Surface Pro 4, a laplet by Microsoft