About the Guitar String Tension Calculator
This string tension calculator works out how hard a string pulls on the neck once it is tuned to pitch. Enter the scale length, the note the string is tuned to and either its gauge (for plain steel or nylon strings) or the manufacturer’s unit weight (for wound strings), and it returns the tension in pounds, newtons and kilograms-force.
Guitarists use tension to build balanced custom sets, to choose heavier gauges for drop tunings or baritone necks, and to check that a lighter set will not feel floppy on a short-scale guitar. Bass players and luthiers use the same physics. A table shows how the tension changes if you tune the same string a few semitones up or down.
Plain-string unit weight is computed from the gauge and the density of steel (7.85 g/cm³) or nylon (1.14 g/cm³). Wound strings have a core and wrap of different metals, so enter their unit weight from the maker’s tension chart for an accurate answer.
With the default inputs, the tension is 16.3 lb. Change any value above to recalculate instantly.
How to use the guitar string tension calculator
- 1Choose plain steel, plain nylon, or wound/custom for strings with a published unit weight.
- 2Enter the gauge in thousandths of an inch, or the unit weight from the maker’s chart.
- 3Enter your scale length in inches or millimetres.
- 4Type the note the string is tuned to, such as E4 or D2.
- 5Read the tension and use the table to see the effect of alternate tunings.
Formula and method
A string vibrating in its fundamental mode has a wavelength of twice the scale length, so the wave speed is 2 × L × F. Wave speed on a string equals √(T ÷ μ), where μ is mass per unit length, which rearranges to T = μ(2LF)². With unit weight UW in pounds per inch and L in inches, dividing by standard gravity (386.09 in/s²) converts mass to pounds-force — the same formula string makers publish.
For a plain string the unit weight is its cross-sectional area times the density of the material. Wound strings must use the published unit weight because the wrap adds mass without adding much stiffness. Results ignore the tiny extra stretch from fretting and string stiffness.
- T
- Tension in pounds-force
- UW
- Unit weight, pounds per inch of string
- L
- Scale length in inches (nut to saddle)
- F
- Frequency of the open string in Hz
- ρ, d
- Material density (lb/in³) and string diameter (in)
Worked examples
.010 plain high E on a 25.5" scale
A .010" steel string weighs about 0.0000223 lb per inch. Tuned to E4 (329.63 Hz) on a 25.5" scale, T = 0.0000223 × (2 × 25.5 × 329.63)² ÷ 386.09 ≈ 16.3 lb, or about 72.5 N — in line with published tension charts for a standard .010 set.
.017 plain G on a 24.75" Gibson scale
G3 is 196.00 Hz. A .017" plain steel string (unit weight ≈ 0.0000644 lb/in) on the shorter 24.75" scale gives about 15.7 lb — roughly 1 lb less than on a 25.5" guitar, which is why Gibson-scale guitars feel slinkier.
Wound string in drop D
A low-E wound string with a unit weight of 0.00038 lb/in tuned down to D2 (73.42 Hz) on a 25.5" scale carries about 13.8 lb. At standard E2 it would be about 17.4 lb, so dropping a whole step loses around a fifth of the tension.
Frequently asked questions
What is a normal guitar string tension?+
Most electric and acoustic guitar strings sit between about 13 and 20 lb each at standard tuning, giving a full set total of roughly 100–180 lb depending on gauge and whether the set is electric or acoustic.
Does a longer scale length increase tension?+
Yes. Tension rises with the square of scale length at the same pitch and gauge, so a 25.5" scale carries about 6% more tension than a 24.75" scale with identical strings.
How much tension do I lose tuning down a half step?+
Tension is proportional to frequency squared, so a half step down cuts tension by about 11% (1 − 2^(−2/12)), and a whole step down by about 21%.
Where do I find a string’s unit weight?+
String makers such as D’Addario publish tension and unit-weight charts for every gauge. Use those figures for wound strings, because their mass depends on the core-to-wrap construction.
Why do heavier gauges suit drop tunings?+
Dropping the pitch lowers tension with the square of frequency. A heavier gauge has more unit weight, which restores the tension and feel lost by tuning down.