# Guitar String Tension Calculator

Calculate guitar string tension from unit weight, scale length, and pitch frequency. Compare tension across tunings and string gauges for electric, acoustic, and bass guitars.

## What this calculates

String tension determines how your guitar feels and sounds. A .046 low E string on a 25.5" Fender scale at standard tuning pulls about 17.5 lbs of force. That same string on a 24.75" Gibson scale pulls about 16.4 lbs, which is why Gibson-scale guitars feel slinkier. This calculator uses the standard D'Addario-style tension formula to help you dial in your perfect setup.

## Inputs

- **String Unit Weight (UW)** (lb/in) — min 0.000001 — Unit weight in lb/in. Example: .046 gauge wound string = 0.0003747 lb/in.
- **Scale Length** (in) — min 15, max 45 — Scale length (e.g., 25.5" Fender, 24.75" Gibson, 34" bass).
- **Target Frequency** (Hz) — min 20, max 5000 — Target pitch frequency in Hz (e.g., low E = 82.41, A = 110, D = 146.83).
- **Quick Tuning Reference** — options: Custom frequency (use Hz above), Low E (E2) - 82.41 Hz, A string (A2) - 110.00 Hz, D string (D3) - 146.83 Hz, G string (G3) - 196.00 Hz, B string (B3) - 246.94 Hz, High E (E4) - 329.63 Hz, Drop D (D2) - 73.42 Hz, Drop C (C2) - 65.41 Hz — Select a standard note or use a custom frequency above.

## Outputs

- **String Tension** (lbs) — Tension in pounds of force.
- **String Tension** (kg) — Tension in kilograms of force.
- **String Tension** (N) — Tension in Newtons.

## Details

The string tension formula is:

T = (UW * (2 * L * F)2) / 386.4

  - T = tension in pounds

  - UW = unit weight of the string in lb/in

  - L = scale length in inches

  - F = frequency in Hz

  - 386.4 = gravitational acceleration in in/s2

**Common Unit Weights (lb/in):**
| Gauge | Plain | Wound |
|-------|-------|-------|
| .009 | 0.00001517 | - |
| .010 | 0.00001874 | - |
| .011 | 0.00002267 | - |
| .024 | - | 0.0001055 |
| .032 | - | 0.0001854 |
| .042 | - | 0.0003178 |
| .046 | - | 0.0003747 |
| .052 | - | 0.0004808 |

Most guitarists are comfortable with per-string tension between 14 and 22 lbs. Below 12 lbs feels floppy; above 25 lbs feels very stiff. When switching to alternate tunings (like Drop D or Drop C), you typically need heavier gauges to maintain adequate tension and avoid a muddy tone.

## Frequently Asked Questions

**Q: What is unit weight and where do I find it?**

A: Unit weight (UW) is the mass per unit length of a string, measured in lb/in. String manufacturers like D'Addario publish unit weight charts for every gauge. You can also find it on their website or in their string tension guide PDF. It varies between plain and wound strings of the same gauge.

**Q: How does scale length affect tension?**

A: Longer scale lengths produce higher tension for the same string and tuning. A 25.5" Fender scale has about 7% more tension than a 24.75" Gibson scale. This is why the same string gauge feels tighter on a Strat than on a Les Paul. Baritone guitars (27-30") and bass guitars (34-35") have even higher tensions.

**Q: What tension should I aim for?**

A: Most players prefer 14-22 lbs per string for standard 6-string guitar. Lighter tension (12-16 lbs) suits players who bend a lot. Heavier tension (18-24 lbs) gives a firmer feel with more volume and sustain. The key is balanced tension across all strings so the guitar feels even from string to string.

**Q: How do I keep tension balanced in drop tunings?**

A: When you drop a string by a whole step, tension drops roughly 20%. To compensate, go up 2-3 gauges on the dropped string. For Drop D, try a .052 instead of .046 for the low string. For Drop C, consider .056 or .060. Many companies sell drop-tuning optimized sets for this reason.

---

Source: https://vastcalc.com/calculators/physics/guitar-string-tension
Category: Physics
Last updated: 2026-04-08