String Tension Calculator
Figure out the right gauge for any tuning and scale length — drop C, drop A, 7-string, 8-string presets included.
| String | Note | Gauge | Tension (lb) | Tension (kg) |
|---|---|---|---|---|
| 1 | E2 | .046 | 31.5 | 14.31 |
| 2 | A2 | .036 | 34.4 | 15.61 |
| 3 | D3 | .026 | 33.8 | 15.32 |
| 4 | G3 | .017 | 14.0 | 6.37 |
| 5 | B3 | .013 | 13.0 | 5.90 |
| 6 | E4 | .010 | 13.8 | 6.24 |
| Total | 140.5 lb | 63.75 kg | ||
Low-tension (< 10 lb) strings sound floppy; high-tension (> 20 lb) strings risk neck bow. Values are approximate — string brand, wrap style, and coating all affect real-world tension.
Why this matters
Dropping to B or A on a 25.5" scale with a standard .010 set leaves strings so loose they rattle. Bumping the low string to .056 or .064 restores playable tension. This calculator uses published unit weights and the standard formula T = (UW × (2Lf)²) / 386.4 to give you a ballpark figure before you swap strings.
FAQ
What tension range is safe?
Most players aim for 12–18 lb per string. Below 10 lb feels floppy; above 20 lb risks neck bow or string breakage.
Why is my drop-C low string so flabby with a .046?
At 25.5" scale, a .046 tuned to C2 is around 9 lb — below the playable threshold. Step up to .052 or .054 for a firmer feel.
Do scale length and tension trade off?
Yes — longer scales (26.5", 27") require less gauge to hit the same tension in low tunings. That's why baritone guitars exist.
Is the formula accurate?
Yes for steel strings with published unit weights. Nylon, flatwound, and coated strings may vary by 5-10%.