Guitar String Tension Calculator
How many pounds (or kg) does each string pull? Pick a gauge, scale length and tuning — get exact per-string tension, a full 6-string set table with total tension, and balance bars. Physics: T = UW × (2 × L × F)² ÷ 386.4, calibrated against D'Addario's published tension chart.
Strings (1 = high E)
| # | Note | Gauge | Type | Hz | Tension |
|---|
Total tension:
Worked examples
The 16.2 lb anchor
A .010" plain steel string, 25.5" scale, tuned to E4 (329.63 Hz):
16.2 lb
UW = 0.00002218 lb/in; 2·L·F = 16,811; T = 0.00002218 × 16,811² ÷ 386.4. D'Addario's published PL010 figure — the calibration anchor of this tool.
Scale length effect
Same .010" string at E4, 25.5" vs 24.75" (Gibson scale):
16.2 → 15.3 lb
Ratio (24.75/25.5)² = 0.942 — a 5.8% drop. Tension follows the square of scale length.
Drop-D on the low string
.046" wound, 25.5" scale, low E (E2) vs dropped D (D2):
16.9 → 13.4 lb
One whole step down = ×0.794 (−20.6%). Players often go one gauge heavier to keep the feel.
Unit weight reference table
The string-specific data behind every calculation, in pounds per inch (lb/in). Plain-steel values scale exactly with diameter squared from the D'Addario PL010 anchor; nickel-wound values are interpolated from D'Addario's published NW026 / NW036 / NW046 tensions.
| Gauge | Type | Unit weight |
|---|
Methodology & sources
The formula
T(lb) = UW(lb/in) × (2 × L(in) × F(Hz))² ÷ 386.4 — the standard string-tension equation published by D'Addario (String Tension Pro) and derived from the physics of a vibrating string (Mersenne's laws). Note frequencies use equal temperament with A4 = 440 Hz.
Where the numbers come from
Unit-weight anchors are reverse-engineered from D'Addario's current published EXL110 tension chart (daddario.com product specs): PL010 16.220, PL013 15.390, PL017 16.580, NW026 18.380, NW036 19.040, NW046 16.910 lb at 25.5" scale. The plain-steel diameter-squared law is verified non-circularly: scaling from the PL010 anchor reproduces D'Addario's independent PL013 (15.39 vs 15.390) and PL017 (16.57 vs 16.580) figures. The equation form and methodology are cross-checked against the Fernandes Guitars string-tension calculator documentation, which uses the same formula and D'Addario unit weights.
Chart revision note
An older D'Addario chart revision listed the NW036 at 19.5 lb and NW046 at 17.5 lb; D'Addario's current published figures are 19.040 and 16.910 lb, which this tool uses. If you compare against an older calculator and see a ~3% difference on heavy wound strings, this revision is why.
Limitations
Wound-string unit weights between and beyond the three anchors are interpolated (log-log fit, max anchor residual 0.1%) and should be treated as estimates — real wound strings vary a few percent by brand, core shape and wrap alloy. Plain-steel values are essentially brand-independent at a given gauge. Nylon, flatwound, phosphor-bronze acoustic and tapered strings need their own mass data and are not modeled.
Safety
Total tension for a typical electric set is 85–120 lb. Large jumps in gauge or tuning a heavy set up to pitch on a long scale can bow the neck or lift an acoustic bridge — check neck relief and action after a change, and see a luthier rather than forcing the truss rod. This tool estimates string force only; it does not assess your instrument's condition.
This calculator measures string force. For scale patterns, chord shapes and reverse scale lookup, see our Guitar Scale Finder.
Frequently asked questions
What is the guitar string tension formula?
String tension in pounds is T = UW x (2 x L x 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 frequency in hertz. It comes from the physics of a vibrating string: tension rises with the square of both scale length and pitch, and linearly with the string's mass per unit length. This calculator implements that formula exactly.
What is unit weight (UW) of a guitar string?
Unit weight is the string's mass per inch of length, in pounds per inch (lb/in). It is the only string-specific input the formula needs: two strings of the same gauge can have different unit weights if their construction differs. This tool uses D'Addario's published unit weights: plain-steel values scaled by diameter squared from the PL010 anchor, and nickel-wound values fitted through D'Addario's published NW026, NW036 and NW046 tensions.
How much tension does a .010 string have at standard tuning?
About 16.2 lb (7.35 kg) on a 25.5-inch scale tuned to E4 (329.63 Hz). This is D'Addario's published figure for their PL010 string and the reference anchor this calculator is calibrated against. On a shorter 24.75-inch (Gibson-style) scale the same string drops to about 15.3 lb, because tension scales with the square of scale length.
What is the total tension of a 10-46 electric guitar set?
About 102.5 lb (46.5 kg / 456 N) at standard tuning on a 25.5-inch scale, using D'Addario EXL110 published tensions: 16.2 + 15.4 + 16.6 + 18.4 + 19.0 + 16.9 lb per string from high E to low E. Lighter sets (9-42) total around 85 lb; heavier sets (11-49) total around 120 lb.
How does scale length affect string tension?
Quadratically: tension is proportional to the square of the scale length. Moving the same string from a 25.5-inch (Fender-style) scale to a 24.75-inch (Gibson-style) scale multiplies tension by (24.75/25.5)^2 = 0.942, a 5.8% drop. A 27-inch baritone scale raises it by (27/25.5)^2 = 1.121, a 12.1% increase at the same pitch.
How much tension do I lose when I tune down?
Tension follows the square of frequency, so tuning down one whole step (two semitones) multiplies tension by (2^(-2/12))^2 = 0.794 - you lose about 20.6% of the tension. Tuning down a half step loses about 10.9%. That is why a familiar set feels noticeably slinkier in Eb or drop-D tuning, and why players often go up a gauge to compensate.
Do wound strings have higher tension than plain strings?
Usually yes, by design. In a typical 10-46 set the wound D, A and low E strings run 17-19 lb while the plain strings run 15-17 lb. Wound strings need extra mass (and hence tension) to reach low pitches at playable gauges, and their flexible wrap-over-core construction feels slinkier than a plain string at the same tension, so makers voice sets with slightly higher wound tension.
What is balanced string tension?
A set where every string pulls with roughly the same force, so bending and fretting feel even across the neck. Standard sets are not balanced - in a 10-46 set the A string (19.0 lb) pulls about 23% harder than the B string (15.4 lb). Balanced-tension sets (like D'Addario's BT series) use compensated gauges, typically with slightly heavier plain strings and lighter wound strings.
Can high string tension damage my guitar?
Excessive total tension can bow the neck, lift the bridge on acoustic guitars, or stress the top. Most electric guitars handle 90-130 lb total without issue, but jumping several gauges heavier (or tuning a heavy set up to pitch on a long scale) is where risk appears. If the action rises or the neck relief changes after a string change, have a luthier check the setup rather than forcing the truss rod yourself.
Do all brands have the same tension at the same gauge?
Plain steel strings are nearly identical across brands at the same gauge, because tension depends only on diameter for a given alloy. Wound strings differ: core diameter, wrap material (nickel-plated steel, pure nickel, cobalt) and winding tightness all change the unit weight. Expect a few percent variation between brands on wound strings; this calculator's wound values are D'Addario-based estimates.
How can I get lower tension without changing my tuning?
Three options: use a lighter gauge (tension scales with diameter squared for plain strings, so .009 instead of .010 drops about 19%), use a shorter scale length guitar, or switch to a more flexible construction such as round-core or pure-nickel wound strings, which feel slinkier at the same measured tension.
What is the difference between a string tension calculator and a scale finder?
This calculator computes the physical pulling force of each string in pounds, kilograms or newtons from gauge, scale length and pitch - useful for choosing gauges and tunings. A scale finder (like our Guitar Scale Finder) is a music-theory tool: given notes or chords it shows which fretboard scale shapes fit. Different questions, different tools.
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