A wall thickness designator used in certain pipe specification systems, such as IPS or EMT, in which a schedule number for a given nominal pipe diameter designates a wall thickness in decimal inches. Typically the same schedule number will designate different wall thicknesses for different nominal pipe diameters. For example, Schedule 40 for 1.5″ IPS pipe is a wall thickness of .145 inches, while Schedule 40 for 2.5″ IPS pipe is a wall thickness of .203 inches. Note that in the IPS system, Schedule 40 is sometimes referred to as “standard” and Schedule 80 as “XS” or “extra-strong”. Schedule is commonly abbreviated “sch.” or “sched.”