Guitar String Tension Calculator
Guitar string tension is the force pulling the string taut between the nut and saddle when it is tuned to pitch. Understanding tension helps you choose the right string gauge for your playing style, tuning, and guitar scale length. The physics are straightforward: tension depends on the string's linear mass density (mass per unit length), the scale length squared, and the frequency squared. Heavier gauge strings have greater mass per unit length, so they need more tension to vibrate at a given pitch. Longer scale lengths also increase tension for a given gauge and tuning. The formula used here comes from the D'Addario string tension guide, which is the industry standard reference for electric, acoustic, and bass guitar string tension data. The unit weight values for each gauge in this calculator are taken directly from D'Addario's published plain steel string specifications. Results are shown in both pounds (the traditional US measurement used in guitar manufacturing) and Newtons (SI units). Most electric guitarists find total string set tensions of 70 to 110 lbs comfortable; classical players prefer lower tensions. Enter your scale length, string gauge, and tuning frequency below to calculate tension instantly.
String tension formula
The string tension formula relates the vibrating mass per unit length to the scale length and vibrating frequency. This is the formula published by D'Addario in their string tension guide and is widely used in the guitar industry.
T (lbs) = unit_weight x (2 x scale_length_in x frequency_Hz)^2 / 386.4
T (Newtons) = T (lbs) x 4.44822
Where:
unit_weight = linear mass density in lbs/in (from D'Addario tables)
scale_length_in = vibrating string length in inches (nut to saddle)
frequency_Hz = target pitch in Hz
386.4 = gravitational constant in in/s^2 (386.4 in/s^2 = 32.2 ft/s^2)
Worked example: .010 string, 25.5-inch scale, E4 (329.63 Hz)
- Unit weight for .010 = 0.000020851 lbs/in
- (2 x 25.5 x 329.63)^2 = (16,811.13)^2 = 282,614,107
- T = 0.000020851 x 282,614,107 / 386.4 = 15.26 lbs
- T = 15.26 x 4.44822 = 67.88 N
Common string tensions reference table (25.5-inch scale, standard tuning)
| String | Note | Frequency (Hz) | .009 gauge (lbs) | .010 gauge (lbs) | .011 gauge (lbs) |
|---|---|---|---|---|---|
| 1 (high E) | E4 | 329.63 | 10.40 | 12.85 | 15.57 |
| 2 (B) | B3 | 246.94 | 8.52 (.011) | 10.74 (.013) | 13.13 (.015) |
| 3 (G) | G3 | 196.00 | 9.93 (.016) | 9.93 (.016) | 11.50 (.017) |
| 4 (D) | D3 | 146.83 | 10.21 (.024w) | 11.94 (.026w) | 12.70 (.027w) |
| 5 (A) | A2 | 110.00 | 11.19 (.032w) | 12.78 (.036w) | 14.61 (.039w) |
| 6 (low E) | E2 | 82.41 | 12.54 (.042w) | 14.44 (.046w) | 17.40 (.052w) |
Values marked (w) indicate wound strings; gauge in parentheses. Data from D'Addario string tension guide. This calculator covers plain steel strings; wound string unit weights differ.
Guitar string tension: frequently asked questions
What is guitar string tension and why does it matter?
String tension is the pulling force exerted along the string between the nut and saddle when it is tuned to pitch. It affects playability, tone, and guitar setup. Higher tension strings feel stiffer under the fingers and require more force to fret and bend; lower tension strings feel more flexible and easier to play. Tension also influences how much force is transferred to the guitar top (for acoustic instruments), affecting sustain and resonance. Electric guitar players often dial in tension by combining scale length, string gauge, and tuning to find their preferred feel.
How does scale length affect string tension?
Tension increases with the square of scale length for a given string gauge and pitch. Moving from a 24.75-inch Gibson scale to a 25.5-inch Fender scale increases tension by approximately (25.5/24.75)^2 = 1.062, or about 6%. This is why guitarists who move from a Gibson-scale guitar to a Fender-scale guitar often find the same gauge strings feel noticeably stiffer. Baritone guitars use scale lengths of 27 to 30 inches to maintain playable tension when tuned to lower pitches.
How do I choose the right string gauge?
Lighter gauges (e.g., .009 to .042 sets) produce lower tension, making bending and vibrato easier and reducing fretting effort. Heavier gauges (e.g., .011 to .050 sets) produce more tension, giving a fuller tone, better tuning stability, and better response for rhythm playing. The right choice depends on your playing style, tuning (lower tunings need heavier gauges to maintain tension), and the guitar's setup. A guitar set up for .009s will need a truss rod adjustment and possibly nut and saddle work if you switch to .011s.
How does drop tuning affect string tension?
Drop tuning lowers the pitch of one or more strings, which reduces tension. Dropping the low E string from E2 (82.41 Hz) to D2 (73.42 Hz) reduces its tension by the ratio (73.42/82.41)^2 = 0.793, or about 21%. This makes the dropped string noticeably looser, which is why many players switch to a heavier gauge on the drop-tuned string, or use a multiscale guitar with a longer bass-side scale length to compensate. Full step-down tunings (e.g., Eb standard or D standard) similarly reduce tension across all strings by roughly 11% per semitone.
What tension range is considered comfortable for playing?
Most electric guitar players find string tensions in the range of approximately 10 to 20 lbs per string comfortable. The high E string on a Strat with .009s at standard tuning is around 10 lbs; the low E with .042s is around 16 lbs. Classical guitarists deal with different tension characteristics because nylon strings have very different unit weights. Acoustic steel string guitars often run higher tensions (15 to 25 lbs per string) due to the structural design of the top and bracing. D'Addario publishes detailed tension charts for all their string sets which are a reliable reference.
Official sources
- D'Addario String Tension Guide (plain steel and wound string unit weights): D'Addario.com.
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology. General information only.