To judge a rope’s tensile strength accurately, you must first understand that tensile strength is used to refer to new rope. This tensile strength is determined under factor conditions and therefore can never accurately represent real world circumstances. Tensile strength also is cut half each time you make a knot. The general guide is that when 8 knots are made in rope the tensile strength is reduced by about 50% depending on the rope. But, above all, tensile strength is used to determine how much weight a rope can handle over a period of time. As long as you understand those basic things, you can accurately judge a rope’s tensile strength for your needs.