P4

P4 may refer to:

Computing

 * Intel Pentium 4, a processor series shipped from 2000 to 2008
 * The P4 power connector, introduced in the ATX12V 1.0 standard to power these and later CPUs
 * The i486DX (P4) model of the Intel 80486 microprocessor, introduced in 1989
 * P4 (programming language), for controlling network data forwarding
 * P4, the Perforce software command line client

Media

 * P4 Radio Hele Norge (PFI), a Norwegian radio company
 * Kanal 24 (Kanal 4), which acquired the Norwegian P4 channel from PFI
 * Sveriges Radio P4, a Swedish radio channel
 * Persona 4, a 2008 video game
 * Periphery IV: Hail Stan, 2019 album by American progressive metal band Periphery

Military

 * Skaraborg Regiment (armoured), a Swedish army unit, designated P 4
 * Peugeot P4, a French military vehicle

Science

 * P4 laboratory, a biosafety level 4 facility
 * Tetraphosphorus (P4), an allotrope of phosphorus
 * Group p4, the plane symmetry group wallpaper group p4
 * Progesterone (Pregn-4-ene-3,20-dione), a steroid hormone
 * Kerberos, the fourth moon of Pluto
 * Perfect fourth, a musical interval
 * Enterobacteria phage P4
 * P4, an EEG electrode site according to the 10-20 system
 * P4 cell, a stage in the Caenorhabditis elegans embryonic development
 * P4-metric, in statistics, a performance metric

Roads

 * P4 road (Latvia)
 * P04 road (Ukraine)

Other uses

 * Papyrus 4, a New Testament manuscript
 * Trans-Pacific Strategic Economic Partnership, or P4, a free trade agreement between Brunei, Chile, New Zealand, and Singapore
 * Prussian P 4, a German steam locomotive
 * Protofour, or P4, a set of standards for model railways