Fret Position Calculator
Calculate the exact position of any fret and the note it produces.
Last updated · View algorithm, constants and default inputs (JSON)
About this calculator
This calculator uses equal temperament: each semitone divides the vibrating length by the twelfth root of two. Fret spacing therefore gets progressively smaller toward the bridge. Note names assume twelve-tone equal temperament and A4 = 440 Hz.
Worked example
calculated with the default values below
Scale length 25.5 in · Fret number 12 · Open string note E · Open string octave 2 Distance from the nut 12.7500 in · Distance from the bridge 12.7500 in · Spacing from the previous fret 0.7582 in · Note at this fret E · Frequency at this fret 164.81 Hz · Semitones above the open string 12
General background references
Disclaimer
These calculators give general estimates. Sizing, pricing, availability and standards vary by brand, retailer and country, so treat the output as a starting point and confirm it against the seller's or authority's own figures.
Implementation source
This record describes the implementation used by this page. It is not independent validation. External references, when available, support only the stated formula or definition; estimates and custom rules retain their own assumptions.
Formula and variables
d_n = L x (1 - 2^(-n/12)); gap_n = d_n - d_{n-1}; f = 440 x 2^((m-69)/12), m = (O+1) x 12 + i + n
- L
- scale length (nut to bridge)
- n
- fret number (0 = open)
- d_n
- distance from the nut
- O
- open-string octave
- i
- open-note semitone index (C=0)
- f
- fret frequency in Hz
Equal temperament: distance from nut = L × (1 − 2^(−n/12)); adjacent fret spacing shrinks by the same twelfth-root-of-two ratio. Note frequency assumes A4 = 440 Hz.
Frequently asked questions
How are fret positions calculated?
The calculator uses equal temperament: each semitone shortens the vibrating string length by a factor of 2^(1/12). For a 25.5-inch scale, fret 12 is halfway along the scale at 12.75 inches. Note and frequency outputs assume twelve-tone equal temperament and A4 = 440 Hz.