2.5

2.5, 2½ or two and a half may refer to:


 * Technology
 * Version 2.5 or v2.5, a designation used in software versioning
 * 2.5D, or 3/4 perspective and pseudo-3D, an attempt to render 3-dimensional images in 2-dimensions
 * 2.5D (machining), technique used in machining to project a plane into 3rd dimension
 * 2.5D (visual perception), effect in visual perception where the 3D environment of the observer is projected onto the 2D planes of the retinas
 * 2.5G phone network; see 2G
 * 2.5-millimeter band


 * Culture
 * Two and a Half Men, American television sitcom
 * Hood Hop 2.5, 2009 album by J-Kwon
 * Jackass 2.5, a 2007 direct-to-video feature; see Jackass Number Two
 * Proposition 2½, Massachusetts statute which limits property tax increases by municipalities