Fret Position Calculator (Guitar and Bass Fret Spacing)
Distance from the nut to any fret of a guitar, bass, ukulele or banjo from its scale length, and the gap to the previous fret.
Results
The dashed line marks the value you entered.
What this tool does
In equal temperament each fret shortens the vibrating string by a factor of the twelfth root of 2, about 1.0595, so the n-th fret sits at L − L ÷ 2^(n/12) from the nut. The 12th fret is exactly half way, and the first fret is about 1/17.8 of the scale, which is where the old 'rule of 18' came from. The gaps shrink as you go up the neck. These are positions along the scale length of an ideal string; real instruments move the bridge saddle back a little to compensate for string stiffness and the stretch when fretting.
Formula
distance from the nut = L − L ÷ 2^(n/12) (12-tone equal temperament)
Variables
| Symbol | Meaning | Unit |
|---|---|---|
l | Scale length (nut to bridge) | mm |
n | Fret number | — |
DN | Distance from the nut to that fret | mm |
DB | Distance from that fret to the bridge | mm |
GP | Gap from the previous fret | mm |
Worked example
- Scale length (nut to bridge)648 mm
- Fret number12
- Distance from the nut to that fret324.00 mm
- Distance from that fret to the bridge324.00 mm
- Gap from the previous fret19.27 mm
Limitations
- The formula assumes ideal conditions: no friction losses, no air resistance and no efficiency losses unless you enter them.
- Mixing units is the most common source of error. Convert every input to the units shown next to each field before calculating.