Pull, on paper
String tension calculator
Tension is how hard the string pulls at a given pitch and vibrating length. The page uses T = UW × (2 × L × F)² / 386.4, with L in inches and UW in pounds per inch, then converts pounds to newtons. The unit weights are historical published D'Addario plain, nickel-wound and phosphor figures. They are not a guarantee of the set currently on a shelf.
Compare a tuning, not a feeling
Put the open-string frequency in A and a lower pitch in B: high E at 329.63 against Eb at 311.13, or low E at 82.41 against drop D at 73.42. Same gauge, same scale, the difference in pounds is the change in pull. A lower pitch pulls less. That can feel easier and it can buzz. The number does not measure your neck relief and it does not tell you which gauge to buy. It tells you the size of the change before you spend the money.
Read it as an estimate
Wound strings of the same diameter from another maker will not match these weights exactly. If you have the maker’s own unit weight, the formula still holds: only UW changes. Scale length is nut to saddle, the vibrating length, not the whole string including the peg.
Questions
- Why 386.4?
- It is the constant in the published chart’s units so the result comes out in pounds-force. Newtons are that result times 4.448.
- Is more tension always better?
- No. Too little buzzes and feels floppy. Too much is harder on the neck and on your hands. The page only does the arithmetic.