Guitar String Tension Calculator

Enter the scale length of your guitar, in inches or millimetres, or pick a common one.
Choose a tuning, or set the note of each string.
Choose a string set, or change the type and gauge of each string. For other brands, choose Custom unit weight and type the value from the maker’s tension chart.
Read the tension of each string, the total, and the bars that show how the strings compare.
Download the results as CSV, or copy them as text.

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How do you calculate the tension of a guitar string from its gauge, scale length and tuning?

String tension is T = UW × (2 × L × f)² ÷ 386.4, where UW is the unit weight of the string in lb/in, L the scale length in inches, f the pitch in Hz and T the tension in pounds. A plain .010 high E (329.63 Hz, unit weight 0.00002215 lb/in) on a 25.5-inch scale pulls with about 16.2 lb (7.4 kg), and a 10–46 electric set totals just over 100 lb. Tension grows with the square of the scale length and of the frequency: tuning down a half step lowers it by about 11% and a whole step by about 21%. This free calculator does the maths for each string with D’Addario unit weights and shows the result in pounds, kilograms or newtons.

What is string tension and why does it matter?

String tension is the pulling force a string exerts when it is tuned to pitch. It decides how a guitar feels: lower tension is looser and easier to bend, but can buzz and feel floppy, while higher tension feels stiffer and gives more punch, but is harder to play and puts more stress on the neck. Three things set it: the thickness and construction of the string (its gauge and unit weight), the length of the vibrating string (the scale length) and the note it is tuned to. Change any of them and the tension changes, which is why a lighter set feels different on a Fender than on a Gibson, and why tuning down makes strings feel slacker. Use this tool to compare a setup before you buy strings or change tuning.