String tension calculator
Tension is the force a tuned string pulls on the neck and the top. It depends on three things: the vibrating length (scale), the pitch and the string's weight per unit length. Pick the instrument, tuning and set, and the calculator gives each string's tension and the set total in pounds, kilograms or newtons.
Tension of a .010–.046 set (D'Addario EXL110) at 25.5″
Standard tuning, 647.7 mm scale, unit weights from the D'Addario chart.
| String | Note | Gauge | kg | lb |
|---|---|---|---|---|
| 1 | E4 | .010 | 7.3 | 16.2 |
| 2 | B3 | .013 | 7.0 | 15.4 |
| 3 | G3 | .017 | 7.5 | 16.6 |
| 4 | D3 | .026w | 8.3 | 18.4 |
| 5 | A2 | .036w | 8.9 | 19.5 |
| 6 | E2 | .046w | 7.9 | 17.5 |
How to use it
- Choose the instrument: electric guitar, steel-string acoustic, classical, bass or ukulele.
- Check the scale length (it starts at the instrument's usual one; measure nut to 12th fret and double it for yours) and choose the tuning.
- Choose the string set. To compare, pick another one under Compare with: the table shows both tensions and the difference in percent.
- For your own set, choose String by string and change each gauge right in the table.
- Switch the unit between lb, kg and N. Your choice is remembered on this device.
Help and explanations
A .010–.046 set on a 25.5″ guitar in standard tuning adds up to about 103.6 lb (47 kg); the same set tuned a whole step down drops to about 82 lb (37 kg). Compare two sets side by side to decide between 9s and 10s, or build a custom set string by string from the gauges in your drawer.
How tension is calculated
The math is D'Addario's: T = UW × (2 × L × F)² ÷ 386.4, with T in pounds, UW the unit weight in pounds per inch, L the scale in inches and F the frequency in Hz. Unit weights come from D'Addario's String Tension Specifications chart, and the calculator's automated test checks the results against the published figures: for the EXL110 (.010–.046) at 25.5″, 16.2 / 15.4 / 16.6 / 18.4 / 19.5 / 17.5 lb, 103.6 lb in total.
Because frequency is squared, tuning down a half step removes about 11% of the tension and a whole step about 21%. Going from a 24.75″ to a 25.5″ scale adds 6% with the same strings, which is why the same 10s feel stiffer on a Fender than on a Gibson.
How much is too much
On a steel-string acoustic, a light .012–.053 set (D'Addario EJ16) on a 25.5″ scale pulls about 163 lb (74 kg); older or lightly built guitars do better with 11s or a lower tuning. On classical guitar, each string sits around 12 to 16 lb (5 to 7 kg), and makers sell sets by tension (normal, hard) instead of gauge. On electric guitar, 15 to 20 lb (7 to 9 kg) per string is what most players find comfortable.
Too slack and the string buzzes and goes sharp when you dig in; too tight and it tires your hand and pulls the neck forward, adding relief. Changed the tension a lot? Check neck relief and string height with the action and relief guide.
Gauges from other brands
Strings of the same construction and gauge weigh almost the same from brand to brand. When a gauge isn't in the D'Addario chart, the calculator estimates its weight: plain steel from the density of steel, and wound strings by interpolating between neighboring gauges of the same construction. Those values are marked with ≈ and, checked against the chart itself, are off by less than 3% (up to 6% on bass strings).
Tips
- To tune down without floppy strings, the string gauge for tuning calculator suggests gauges that keep your set's tension.
- Changed gauges? Set the intonation of each string with the intonation checker.
- Even tension across the set gives a more uniform feel; a string that sticks out on the chart will feel stiffer or floppier than its neighbors.
- On a floating tremolo, changing total tension changes the spring balance: retune with the guitar tuner.
Frequently asked questions
What is the tension of a set of 10s?
At 25.5″ in standard tuning, D'Addario's EXL110 (.010–.046) totals 103.6 lb, about 47 kg: 15 to 20 lb per string. On a 24.75″ scale, the same set is about 6% lighter, around 97.5 lb.
How do I convert string tension from pounds to kg?
Multiply by 0.4536. 17.5 lb is 7.9 kg; 100 lb is 45.4 kg. For newtons, multiply pounds by 4.448.
9s or 10s: how much difference?
A .009–.042 set has about 18% less tension than a .010–.046 on the same guitar (about 85 lb against 103.6 lb at 25.5″). Bends get easier, but it buzzes more with low action and a heavy pick attack.
Does tuning down reduce string tension?
A lot: a half step down removes about 11% and a whole step about 21% from each string. To keep the same feel, go up a gauge.
What is the tension of classical guitar strings?
With a normal-tension set (like D'Addario EJ45) at 650 mm, 11.7 to 15.7 lb (5.3 to 7.1 kg) per string, about 84 lb (38 kg) in total. Hard-tension sets (EJ46) are about 4% higher.
Does string tension depend on the brand?
It depends on the string's weight, and strings of the same construction and gauge weigh nearly the same. Hex cores, bronze or nickel wrap and coatings shift the weight a little, which is why gauges outside the chart show as estimates.