Guitar String Tension Calculator
Guitar string tension in pounds and newtons from scale, string, and tuning.
What it does
String tension decides both feel and setup: too little and strings buzz and drift, too much and they snap or bow the neck. Three inputs fix it exactly, the string unit weight, the scale length, and the pitch.
The tool above takes scale length with a 10-46 set preset and detune steps. It returns per-string pull in pounds and newtons plus the full set total.
The default high E .010 on a 25.5 in scale at standard pitch pulls 16.2 lb (72.1 N), inside a 102.5 lb set. The metric mirror of 647.7 mm reads the same.
Physics follows OpenStax wave speed with Georgia State HyperPhysics behind it. Both give T from (2 x L x f)^2 x mu, and preset weights reproduce maker chart tensions.
How to use
- Pick inches or millimeters.
- Enter the scale length nut to saddle.
- Pick the string preset.
- Enter detune semitones, 0 for standard.
- Read per-string tension first.
- Check the full set total beside it.
Formula
- UW
- String mass per inch, per gauge and build.
- L
- Vibrating length, nut to saddle.
- F
- Pitch in Hz at A440 tuning.
- 386.4
- Gravity constant, 386.4 in/s^2.
Unit weight is pounds per linear inch from maker tables; metric converts to kg per meter first (x 17.858). Detune multiplies frequency by 2^(semitones/12). Real strings stretch a few percent off ideal, and wound mass already sits inside each preset.
Worked example
Example: high E on a 25.5 in scale
Imperial defaults: 25.5 in scale, high E string, standard tuning.
- Preset: high E .010 at E4 329.63 Hz.
- Scale: 25.5 in, standard tuning.
- Core: (2 x 25.5 x 329.63)^2 = 282,614,107.
- Tension: unit weight x core / 386.4 = 16.2 lb.
- Newtons: 16.2 x 4.44822 = 72.1 N.
- Set total: all six sum to 102.5 lb.
- Tool shows 16.2 lb, 72.1 N, 102.5 lb total.
Reference table
| String | Note | Tension |
|---|---|---|
| PL010 high E | E4 | 16.2 lb |
| PL013 B | B3 | 15.4 lb |
| PL017 G | G3 | 16.6 lb |
| NW026 D | D3 | 18.4 lb |
| NW036 A | A2 | 19.0 lb |
| NW046 low E | E2 | 16.9 lb |
Limits
- Ideal string math; stretch shifts real pull.
- Presets model one 10-46 nickel set.
- Fretted notes shorten length past the nut.
- Old strings break below rated pull.
Common mistakes
- Mixing inch weights with metric length.
- Ignoring setup after gauge jumps.
- Tuning wound G math onto plain strings.
- Chasing exact decimals past stretch.
- Forgetting detune squares the drop.
Try it yourself
Quick checks. Answers sit tucked under each question.
Low E .046 at 25.5 in standard?
Low E preset recomputes 16.9 lb (75.2 N), set still 102.5 lb.
High E on a 24.75 in scale?
Length ratio squared: 16.2 x (24.75/25.5)^2 = 15.3 lb (67.9 N).
High E one semitone down?
Frequency x 0.9439, tension x 0.8909: 14.4 lb (64.2 N).
Questions
What sets string tension?
Unit weight, scale length, and frequency: T = UW x (2 x L x F)^2 / 386.4 in pounds.
Does scale length change feel?
Longer scales pull harder: tension rises with the square of length, about 6% from 24.75 to 25.5 in.
What happens in drop tunings?
Tension falls with the square of frequency, so full step down cuts every string near 20%.
Wound vs plain at one gauge?
At equal gauge and pitch, wound strings pull harder because wraps add mass per inch.
What total pull is normal?
Most electric sets total 90 to 110 lb. Past that, check neck relief and intonation.
Do heavier strings always pull more?
Yes. Heavier gauges weigh more per inch, so 9s to 10s adds roughly 10% across the set.