Fret Spacing Calculator
Enter the scale length and number of frets to compute the exact distance from the nut to each fret, the spacing between adjacent frets and the remaining scale length β using the 12th-root-of-2 rule of equal temperament. Ideal for lutherie, mods and repairs.
Formula
FAQ
How is fret spacing calculated?
Using equal temperament: each semitone raises pitch by a factor of 2^(1/12), so the vibrating string length shrinks proportionally. Distance to fret n from the nut = scale length Γ (1 β 2^(βn/12)). This holds for any instrument fretted in semitones.
Why is the 12th fret exactly at half the scale?
The 12th fret is the octave (frequency doubles). Since 2^(β12/12)=0.5, position = scale Γ (1 β 0.5) = half the scale. It is the key check that your calculation is correct.
What is the scale length?
The vibrating string length from the nut to the bridge (before compensation). A typical electric guitar is about 25.5β³ (648 mm), classical about 25.6β³ (650 mm), bass about 34β³ (864 mm).
How do I handle real bridge compensation?
Real strings need the bridge moved slightly back (compensation) for accurate octaves. This tool gives the ideal geometric positions; fine-tune the saddle after measuring at the 12th fret.