The actual breaking strength of any individual rope is determined by pulling the rope at a slow, steady rate in a straight line, to the point of destruction.

The rated minimum breaking strength of a rope is determined using the “3 sigma” method. This means the minimum breaking strength is calculated by taking the mean or average breaking strength of 5 rope samples, and subtracting 3 standard deviations. Statistically, this creates a confidence level of 99.87% that any sample of rope will actually be stronger than the quoted minimum breaking strength.