Guitar Fret Spacing Calculator
Enter the scale length and the fret number.
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Guitar Fret Spacing Calculator by TheCalcTools
How the Guitar Fret Spacing Calculator works
Each fret shortens the vibrating string so the pitch rises one semitone. In equal temperament the remaining length shrinks by 2^(1/12), so fret n sits at L × (1 − 2^(−n/12)) from the nut.
The 12th fret is exactly halfway along the scale length. Builders add a little compensation at the saddle to keep intonation true.
The formula
Worked example
Using the default values shown in the calculator:
| Scale length (mm) | 648 |
|---|---|
| Fret number | 12 |
- On a 648 mm scale the 12th fret is 324.00 mm from the nut.
Result:
| Distance from the nut (mm) | 324.00 |
|---|---|
| Spacing from the previous fret (mm) | 19.27 |
| Distance to the bridge (mm) | 324.00 |
| Distance from the nut (inches) | 12.756 |
Frequently asked questions
What is the old 17.817 rule?
Dividing the remaining length by 17.817 gives the next fret: it is 1 ÷ (1 − 2^(−1/12)), the same rule.
Sources and further reading
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This calculator gives estimates for information only. Check important results independently before you rely on them. See our disclaimer.