The common torque ratings for bolts used depend on many different factors such as the bolt size, bolt material, number and type of threads and the condition of the bolt. The torque rating for various bolts also depends on the use and the purpose of the bolt.
Torque is the force resulting from the twist. The torque causes the rotation to the shaft of the bolt. Torque is expressed in terms of inch pounds or foot pounds. A string wound around a pulley gives an accurate value of torque. The torque ratings for the different types of bolt depend on the size. The toque rating for aluminum bolt ranges from 1.4 inch-pound to 19.2 inch-pound and the torque for stainless steel range from 2.5 inch-pound to 31.7 inch-pound. Structural bolts also have different torque ratings.