P40 may refer to:

Proteins Interleukin-12 subunit beta Neutrophil cytosolic factor 4 Ribosomal protein SA

Vehicles

Carro Armato P 40, an Italian tank Curtiss P-40 Warhawk, an American military aircraft Percival Prentice, a British trainer aircraft Pottier P.40, a French sport aircraft P40 Genesis, an American locomotive

Other uses Huawei P40, a smartphone Kel-Tec P-40, a pistol Nonidet P-40, a detergent P-40 APPLE mine, a Vietnamese mine P-40 radar, a Soviet radar Papyrus 40, a biblical manuscript Phosphorus-40, an isotope of phosphorus ThinkPad P40 Yoga, a laptop P40, a Nissan P engine P40, prohibited airspace over Thurmont, Maryland, the site of Presidential retreat Camp David Nvidia Tesla P40, a GPU accelerator