Tensile strength relates to the stress and strain to which paper is subjected in its many end use applications. It is defined as the maximum force required to break a paper strip of a given width under prescribed laboratory conditions. Tensile strength is usually defined as pounds-per-inch width of the testing strip, or as kilogrammes per 15-millimeter width. Tensile strength is measured in both the grain and cross-grain directions, however, it is always greater in the grain direction.