CALCULATOR
Fret Spacing Calculator
Work out where every fret goes, and how far off it would be in cents.
Scale lengthmm
Twelfth fret from the nut
First fret spacing mm
Worst error cents
Nearest common scale
Half-scale check:
Fret position = L × (1 − 1 / ratio)
Equal temperament ratio = 2^(n / 12)
Error in cents = 1200 × log₂(ratio ÷ 2^(n/12))
Twelfth fret = L − L/2, which is the half-scale check
Equal temperament ratio = 2^(n / 12)
Error in cents = 1200 × log₂(ratio ÷ 2^(n/12))
Twelfth fret = L − L/2, which is the half-scale check
How to read thisFret positions come from the twelfth root of two for equal temperament, and from simple ratios for just and Pythagorean tuning. The differences between them are small at the nut and large at the twelfth fret, which is why temperament is a real choice. The figures are estimates built on standard approximations — check them against your own instrument before you make a decision that matters.
Educational tool. Nothing you type here leaves your browser. This is a reference calculation, not a measurement of your instrument, and it is not a substitute for the manufacturer’s specifications.