String Tension Calculator
Calculate the physical tension of a musical instrument string based on mass, length, and pitch.
The calculated string tension is:
Understanding String Tension Physics
String tension is the amount of force exerted by a string pulled taut between two points, such as the nut and the bridge of a guitar. Getting the tension right is critical for playability, intonation, and preventing damage to the instrument's neck.
The Calculation Formula
This calculator uses the standard physics formula for a vibrating string:
T = (UW × (2 × L × f)²) / 386.4
- T: Tension (lbs)
- UW: Unit Weight (lbs per linear inch)
- L: Scale Length (inches)
- f: Frequency (Hertz)
- 386.4: Gravitational constant conversion factor
Common Frequency Reference (Standard Tuning)
| Note | Standard Frequency (Hz) |
|---|---|
| E2 (Low E) | 82.41 Hz |
| A2 | 110.00 Hz |
| D3 | 146.83 Hz |
| G3 | 196.00 Hz |
| B3 | 246.94 Hz |
| E4 (High E) | 329.63 Hz |
Why Calculate Tension?
Whether you are a luthier building a custom instrument or a guitarist experimenting with "drop tunings," knowing the tension helps you select the correct string gauge. If the tension is too low, the string will feel "floppy" and buzz against the frets. If it is too high, you risk snapping the string or warping the instrument's neck.
Example Calculation
If you have a 25.5-inch scale guitar and use a .010 gauge High E string (Unit Weight approx 0.00002215) tuned to 329.63 Hz:
T = (0.00002215 × (2 × 25.5 × 329.63)²) / 386.4 = 16.2 lbs