You enter a scale length, string gauge (diameter in inches), and tuning note. The tool derives the unit weight of a plain steel string from the gauge using the density of music wire (0.284 lb/in³), then applies the Mersenne equation to compute tension. It assumes a plain (unwound) steel string — wound strings have a lower effective density and will show higher tension than their actual value.
Wound strings have a steel core wrapped in a secondary wire, which changes the effective mass per unit length. This calculator uses the plain-steel density, so wound strings (typically the lower 3–4 strings on a guitar) will read higher than their real tension. Manufacturers publish unit-weight charts for wound sets that give more accurate values.
Tension rises with the square of scale length. A Fender-scale guitar (25.5″) puts about 6% more tension on the same gauge and pitch than a Gibson-scale (24.75″). This is why shorter-scale guitars often feel "slinkier" with the same string set.
Most electric guitarists prefer per-string tension between about 14–18 lbs. Jazz players often go higher (heavier gauges), while shredders and benders tend toward the lower end. There is no single right answer — it depends on playing style, action height, and personal feel.
No. Nylon, gut, and synthetic strings have very different densities than steel. This calculator's density constant (0.284 lb/in³) is specific to plain steel music wire. Use manufacturer data sheets for non-steel strings.
Estimate only. Results reflect your inputs and standard formulas. Double-check important decisions independently.