String tension
Guitar String Tension Calculator
Pick a scale length, a tuning and a gauge for every string. The calculator returns the tension on each string and the total your instrument is holding, in pounds or kilograms, with a warning on any string that falls outside the range that instrument normally lives in. A second setup sits below it so you can compare two tunings or two gauge sets side by side.
Setup A
Every number below follows these choices. Changing one recalculates the whole set.
Scale length is the vibrating length from nut to bridge. A 25.5 in Fender-style scale is the reference for most published electric guitar tensions.
Solid steel plain strings with round-wound strings that use a nickel-plated steel wrap.
Easy bends, the lightest common electric set.
Total set tension
84.9 lb
38.5 kg · 6strings · 25.5 in scale
Usual band for this instrument: 10–26 lb per string. A typical six-string electric set runs about 15–19 lb per string; acoustic sets about 23–30 lb.
| String | Target note | Gauge (in) | Type | Tension | Notice |
|---|---|---|---|---|---|
| 6 | E282.41 Hz | 14.7 lb17.3% of the set | — | ||
| 5 | A2110.00 Hz | 15.5 lb18.2% of the set | — | ||
| 4 | D3146.83 Hz | 15.8 lb18.6% of the set | — | ||
| 3 | G3196.00 Hz | 14.7 lb17.3% of the set | — | ||
| 2 | B3246.94 Hz | 11.0 lb13.0% of the set | — | ||
| 1 | E4329.63 Hz | 13.2 lb15.5% of the set | — |
Every string sits inside the usual 10–26 lb band for this instrument.
Compare two setups
Setup B is measured with the same arithmetic as setup A. The last column of its table is the difference against setup A, string by string, so you can see which strings gain the most from a change.
25.5 in (647.7 mm) from nut to bridge — Fender-style (Stratocaster, Telecaster).
Heavier bottom for Drop C and C standard.
Total set tension (B)
116.1 lb
52.7 kg · 6 strings · 25.5 in scale
Usual band for this instrument: 10–26 lb per string. A typical six-string electric set runs about 15–19 lb per string; acoustic sets about 23–30 lb.
Setup B is 31.2 lb heavier than setup A.
| String | Target note | Gauge (in) | Type | Tension (B) | Δ vs A |
|---|---|---|---|---|---|
| 6 | C265.41 Hz | 16.1 lb13.9% of the set | +1.5 lb | ||
| 5 | G298.00 Hz | 22.7 lb19.6% of the set | +7.3 lb | ||
| 4 | C3130.81 Hz | 21.9 lb18.8% of the set | +6.1 lb | ||
| 3 | F3174.61 Hz | 18.2 lb15.7% of the set | +3.5 lb | ||
| 2 | A3220.00 Hz | 18.5 lb16.0% of the set | +7.5 lb | ||
| 1 | D4293.66 Hz | 18.6 lb16.0% of the set | +5.4 lb |
Every string in setup B sits inside the usual 10–26 lb band for this instrument.
How the tension calculator works
- Set the instrument and tuning. The tuning decides the target pitch of every string, and that pitch is half of the tension calculation. A drop tuning lowers the pitch on the strings you drop, so those strings lose tension unless you go heavier.
- Set the scale length. This is the vibrating length from the nut to the bridge saddle, and it is squared in the formula: a scale that is 6% longer pulls about 12% harder with the same strings. Common lengths are listed by instrument; anything from 10 to 42 in can be typed in inches or millimetres.
- Choose the material and a starting gauge set. The preset sets are ordinary commercial sets listed low string first. Every gauge, and whether that string is plain or wound, can be edited afterwards.
- Read the table. Each string shows its target note, the gauge, its tension, and its share of the total. The notice column flags a string that falls outside the band that instrument normally lives in.
- Compare two setups. Setup B repeats the same controls. Its final column is the difference against setup A on each string, which is the fastest way to see whether a heavier set or a shorter scale actually solves the string you were worried about.
The formula behind the numbers
Tension is T = UW × (2 × L × F)² / 386.4, where UW is the string's unit weight in pounds per inch, L is the vibrating scale length in inches, F is the target frequency in hertz and 386.4 is the standard gravitational constant in inches per second squared. Because the scale length and the frequency are both inside the square, tension rises with the square of each: double the scale and you quadruple the tension, and raising a string by an octave quadruples it too.
The target frequency comes from twelve-tone equal temperament at A4 = 440 Hz, the same arithmetic the site's note to frequency converter uses, so the hertz shown in this table match the tuning library.
Where the unit weights come from
Unit weight is the mass of one inch of string, and it is the number most calculators hide. This page models it rather than asking you for it: a plain string is solid material, so its unit weight is the cross-section area times the density — steel at 0.283 lb/in³, nylon at 0.041 lb/in³, fluorocarbon at 0.064 lb/in³. A wound string is not a solid rod of its outer diameter, because the wrap leaves gaps and the core-to-wrap ratio changes with gauge, so wound unit weight is taken from a calibrated model of round-wound construction instead.
The nickel-wound model reproduces published tensions for common commercial sets to within about 1%: a regular 10–46 set on a 25.5 in scale comes out at 103.7 lb total, and an 11–49 set at 19.7, 21.6 and 21.3 lb on the three wound strings, matching the figures string makers publish. Phosphor bronze is about 12% denser than nickel-plated steel and the wrap carries most of a wound string's mass, so a bronze string is modelled about 7% heavier than the same gauge in nickel.
| Setup | Detail | Total tension |
|---|---|---|
| Electric guitar, 10–46, standard tuning | 25.5 in scale, nickel-plated steel. | 103.7 lb (47.0 kg) |
| Acoustic guitar, 12–53, standard tuning | 25.5 in scale, phosphor bronze. | 159.0 lb (72.1 kg) |
| Drop C electric, 12–56 | 25.5 in scale, nickel-plated steel, low string at C2. | 116.1 lb (52.7 kg) |
| Four-string bass, 45–100, standard tuning | 34 in scale, nickel-plated steel. | 165.8 lb (75.2 kg) |
| Soprano ukulele, nylon GCEA | 15 in scale, nylon, reentrant fourth string. | 25.5 lb (11.6 kg) |
What a comfortable tension looks like
There is no single correct number, but every instrument family has a range its strings are designed to sit in. These are the bands the notice column uses:
| Instrument | Usual tension per string | What it means |
|---|---|---|
| Electric guitar | 15–19 lb | A regular 10–46 set on a 25.5 in scale. Below about 12 lb a string starts to feel rubbery and loses tuning stability. |
| Acoustic guitar | 23–30 lb | Phosphor bronze sets are deliberately heavier than electric sets. A 12–53 set totals roughly 159 lb. |
| Bass | 35–48 lb | A four-string 45–100 set on a 34 in scale totals about 170 lb. A low B on a 34 in scale is where short scales start to struggle. |
| Ukulele | 5–9 lb | Nylon and fluorocarbon pull far less than steel. Judging a ukulele by guitar numbers is the usual mistake. |
| Mandolin | 19–24 lb | A short scale and a high pitch keep mandolin tension close to an acoustic guitar's. |
| Banjo | 9–14 lb | Light strings on a long scale. The short fifth string sounds only about three quarters of the scale, which this calculator accounts for. |
Worked examples
A regular 10–46 set on a 25.5 in scale in standard tuning comes out at 17.5 lb on the low E, 19.5 lb on the A, 18.4 lb on the D, 16.6 lb on the G, 15.4 lb on the B and 16.2 lb on the high E — 103.7 lb across the set. That is the shape most electric sets are designed around: roughly even, with the wound strings doing slightly more work.
The same strings dropped to Drop C put the low string at C2 instead of E2. Even with the heavier .056 the drop-C set uses, the low string ends up at about 16 lb rather than 17.5, which is why drop tunings are usually paired with a heavier bottom string and sometimes a longer scale. Moving the same set to a 24.75 in scale removes about 6% of the tension everywhere without changing a single gauge, since tension follows the square of the scale length.
A 9–42 light set tuned a whole step down on a 24 in scale drops the top two strings under 10 lb. Nothing breaks; the strings simply feel loose and drift out of tune when you play hard. That is the case the notice column is for.
Limits worth knowing
- Tension is calculated from a unit-weight model, not measured from the strings in your hand. Expect a few percent of difference against a specific manufacturer's published chart, and treat this page as a way to compare setups rather than to certify one.
- Plain and wound are chosen per string and can be switched by hand. Octave strings in a 12-string set and light bass strings do not always follow the usual .020 cutoff, so check them if the numbers look wrong.
- Wound nylon and wound fluorocarbon strings are not modelled separately; those materials are calculated as solid monofilament, which overstates the tension of the rare wound versions.
- Equal temperament at A4 = 440 Hz only, matching the site's tuning library. No just intonation, stretch tuning, or compensation for a guitar's setup.
- Tension is not the only limit. A string can be at a comfortable tension and still be too thick for the nut slot, the saddle, or the tuner post, and a neck can still move under a heavy set even at a tension the numbers call normal.
- Everything runs in your browser. The scale length, gauges and tuning you enter are never sent anywhere or stored.
Questions
How is guitar string tension calculated?
Tension is UW × (2 × L × F)² / 386.4, where UW is the string's unit weight in pounds per inch, L is the scale length in inches and F is the target frequency in hertz. The gauge decides UW, the instrument decides L and the tuning decides F. Because L and F are both squared, small changes in either move tension a lot.
What tension should my strings be?
For an electric guitar, about 15–19 lb per string, or roughly 100–110 lb across a six-string set. Acoustic sets run 23–30 lb per string, bass 35–48 lb, and ukulele only 5–9 lb because nylon is far lighter than steel. The useful question is usually whether one string sits far from the others, not whether the total hits a particular number.
Why does a longer scale length mean more tension?
A longer string needs more tension to reach the same pitch, and the relationship is squared: going from a 24.75 in Gibson scale to a 25.5 in Fender scale adds about 6% tension with identical strings and tuning. That is why baritone guitars are built long, and why the same set feels stiffer on a longer instrument.
Do drop tunings really need heavier strings?
The dropped strings do. A regular 10–46 set with the low string at C2 lands near 10 lb on a 25.5 in scale, well under the 15 lb or so it carries at E2. Drop-C sets use a .056 or heavier bottom string for exactly this reason, and a longer scale helps as well.
Can I use this for bass, ukulele, mandolin or banjo?
Yes. Choose the instrument and the preset gauges update to a typical set for it, and the material switches to nylon for ukulele and phosphor bronze for mandolin. The banjo's short fifth string is calculated with its shorter sounding length rather than the full scale.
Why is my number different from the string maker's chart?
Manufacturers publish figures for their own construction: core shape, wrap alloy, plating and winding tension all differ. This page uses one calibrated model so every instrument is comparable. It lands within about 1% on common nickel-wound electric sets, and a few percent elsewhere — plenty for comparing gauges and tunings, not a substitute for the maker's own chart when you need their exact number.
Where to go next
- Guitar tuning frequency chart — the target hertz for every open string in the tuning library, which is the pitch this calculator turns into tension.
- Note to frequency converter — check the exact hertz of a fretted note at any A4 reference before you work out what it would pull.
- Guitar tuning identifier — work out which named tuning your current strings are already in.
- Guitar won’t stay in tune after restringing — the other reasons a string drifts once tension and gauge are ruled out.
- Drop B tuning chords and Drop B bass tuning — what to play once the strings are at the tension this page reports.