MusicReasonPitch, Tuning, Intonation, and Fret Geometry
How much tension does this string need?
Declare a string's own unit weight (mass per unit length, from the manufacturer), the scale length, and the target pitch. This tool estimates the resulting tension. It requires your own unit-weight figure and never derives one from a nominal gauge number, since that relationship depends on the string's specific construction.
Answer
Want to learn more? Fretboards, Tunings, Capos, and Sounding Pitch
Understand
A string's tension depends on three things: how heavy it is per unit length, how long the vibrating portion is, and how high it must be tuned. Manufacturers publish a unit-weight figure for each gauge and material because the same nominal gauge number can carry different actual weight depending on winding and core construction, which is exactly why this tool asks for that figure directly rather than a gauge number alone.
Worked examples
Doubling the target frequency, holding unit weight and scale length fixed, quadruples the estimated tension, since tension scales with the square of frequency. Doubling the scale length instead, holding weight and frequency fixed, also quadruples the tension, since length appears squared in the same formula.
Method and limitations
The formula is T = UW × (2Lf)², with unit weight in kilograms per meter, scale length in meters, and frequency in Hz, giving tension in newtons; a pounds-force conversion is shown alongside it. This is an idealized estimate for an ideal flexible string; it does not account for the string's own stiffness, the exact break angle at the nut or bridge, or the instrument's own construction and hardware, and it makes no claim about a safe setup range or breakage risk for any specific instrument.
Because tension depends on frequency squared, small pitch differences compound quickly: tuning a string down a whole step lowers its estimated tension by roughly 20%, while tuning it up a whole step raises it by roughly 26%, an asymmetry that surprises many players expecting a simple, symmetric change. This is also why a single set of strings designed for one tuning can feel noticeably slack or overly stiff when used at a very different tuning without a compensating gauge change.