Hi: Process capability ratio= (USL-LSL)/ 6 sigma where USL= upper specification limit LSL= lower specification limit sigma= process standard deviation Process capability refers to the uniformity of the process. ( measure of the uniformity of the output). Basically the process capability ratio is a measure of the ability of the process to manufacture product that meets specifications. Adil Nasir Process Engineer Pycon Inc. ################################################################ TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################