Why Do You Need To Know About String Tension? D’Addario receives hundreds of inquiries each year from players who have questions or problems to solve related to string gauges or tensions. To assist players in determining the appropriate string for their needs, we created the Online String Tension Guide, a complete book of charts for determining the appropriate string to be used in just about any situation. The guide includes formulas for determining string tension for any string on any instrument type or scale length using three basic measurements: the Unit Weight, the Scale Length of the instrument, and the Frequency of the string. If scientific formulas aren’t your strong point, we have pitch/tension charts for just about every string we make, including electric guitar, acoustic guitar, classical guitar, and bass guitar