Building or refretting a guitar, bass, ukulele or other fretted instrument? Enter the scale length and number of frets to get every fret's exact distance from the nut, the spacing between frets and the distance to the saddle, ready to download as a CSV slotting chart.
Last updated:
Units
Nut to saddle; twice the nut-to-12th-fret distance.
Enter your values to see the result.
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How to use the Guitar Fret Position Calculator
Choose inches or millimetres.
Enter the scale length: the distance from the nut to the saddle, or pick a preset.
Enter the number of frets on the fingerboard.
Read the fret table: always measure each slot from the nut, not from the previous fret, to avoid adding up errors.
Download the CSV to print or import into CAD as a slotting template.
The fret position formula
dn = L − L ÷ 2n/12
L = scale length (nut to saddle), n = fret number, dn = distance from the nut
Spacing between frets n − 1 and n = dn − dn−1; distance from fret n to the saddle = L ÷ 2n/12
The 12th fret is at L ÷ 2 and the 24th at 3L ÷ 4
Example: on a 25.5 in scale, fret 5 is at 25.5 − 25.5 ÷ 25/12 = 25.5 − 19.103 = 6.397 in from the nut.
Fret positions for common scale lengths
Distance from the nut to each fret.
Fret
25.5 in
24.75 in
25 in
650 mm
34 in bass
1
1.431
1.389
1.403
36.5
1.908
2
2.782
2.700
2.728
70.9
3.709
3
4.057
3.938
3.978
103.4
5.410
4
5.261
5.106
5.157
134.1
7.014
5
6.397
6.208
6.271
163.1
8.529
6
7.469
7.249
7.322
190.4
9.958
7
8.481
8.231
8.315
216.2
11.308
8
9.436
9.158
9.251
240.5
12.581
9
10.338
10.034
10.135
263.5
13.783
10
11.189
10.860
10.969
285.2
14.918
11
11.992
11.639
11.757
305.7
15.989
12
12.750
12.375
12.500
325.0
17.000
15
14.779
14.344
14.489
376.7
19.705
17
15.948
15.479
15.636
406.5
21.264
19
16.990
16.491
16.657
433.1
22.654
21
17.919
17.392
17.567
456.8
23.892
22
18.344
17.805
17.985
467.6
24.459
24
19.125
18.562
18.750
487.5
25.500
Frequently asked questions
How do you calculate fret positions?
In 12-tone equal temperament each fret shortens the vibrating string by a factor of 2^(1/12). The distance from the nut to fret n is L − L ÷ 2^(n/12), where L is the scale length. On a 25.5 in scale, fret 1 is 25.5 − 25.5 ÷ 1.05946 = 1.431 in from the nut.
What is the 17.817 rule?
Dividing the remaining string length by 17.817 gives the next fret's spacing. It is a close approximation of 1 − 2^(−1/12) ≈ 1/17.817. Older luthiers used 18, which places frets slightly flat; the exact formula used here avoids that error.
Where is the 12th fret?
The 12th fret is exactly half the scale length from the nut, because halving the string length raises the pitch one octave. On a 25.5 in guitar it is at 12.75 in.
What scale length is my guitar?
Measure from the nut to the 12th fret and double it. Common scales are 25.5 in (Fender Stratocaster and Telecaster), 24.75 in (Gibson Les Paul and SG), 25 in (PRS), 650 mm (classical guitar), 34 in (standard bass) and 13 in (soprano ukulele).
Why measure from the nut instead of between frets?
Each spacing is rounded slightly, and those rounding errors add up when you measure fret to fret. Measuring every slot from the nut (or the nut line on a template) keeps each fret accurate.
Does the bridge sit exactly at the scale length?
No. The saddle is set slightly behind the theoretical scale length (compensation), typically a few millimetres and more for thicker strings, because pressing a string down stretches it and raises its pitch. Fret positions still use the nominal scale length.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.