Fret calculator
Enter the scale length (nut to saddle, before compensation) and how many frets the neck will have. The calculator lists each fret's distance from the nut, from the previous fret and to the saddle, in inches or millimeters. On a 25.5″ Fender-style scale, the 1st fret sits 1.431″ (36.35 mm) from the nut and the 12th lands exactly halfway, at 12.750″.
Fret distance from the nut (mm)
Equal-temperament math for four common scales: classical guitar, 25.5″ and 24.75″ electric guitars and 34″ bass.
| Fret | 650 mm | 647.7 mm (25.5″) | 628.65 mm (24.75″) | 863.6 mm (34″) |
|---|---|---|---|---|
| 1 | 36.48 | 36.35 | 35.28 | 48.47 |
| 2 | 70.92 | 70.66 | 68.59 | 94.22 |
| 3 | 103.42 | 103.05 | 100.02 | 137.40 |
| 4 | 134.09 | 133.62 | 129.69 | 178.16 |
| 5 | 163.05 | 162.47 | 157.69 | 216.63 |
| 6 | 190.38 | 189.71 | 184.13 | 252.94 |
| 7 | 216.18 | 215.41 | 209.08 | 287.22 |
| 8 | 240.53 | 239.67 | 232.63 | 319.57 |
| 9 | 263.51 | 262.58 | 254.85 | 350.10 |
| 10 | 285.20 | 284.19 | 275.83 | 378.92 |
| 11 | 305.67 | 304.59 | 295.63 | 406.12 |
| 12 | 325.00 | 323.85 | 314.33 | 431.80 |
| 13 | 343.24 | 342.03 | 331.97 | 456.04 |
| 14 | 360.46 | 359.18 | 348.62 | 478.91 |
| 15 | 376.71 | 375.38 | 364.34 | 500.50 |
| 16 | 392.05 | 390.66 | 379.17 | 520.88 |
| 17 | 406.53 | 405.09 | 393.17 | 540.12 |
| 18 | 420.19 | 418.70 | 406.39 | 558.27 |
| 19 | 433.09 | 431.56 | 418.86 | 575.41 |
| 20 | 445.26 | 443.69 | 430.64 | 591.58 |
| 21 | 456.75 | 455.14 | 441.75 | 606.85 |
| 22 | 467.60 | 465.95 | 452.24 | 621.26 |
| 23 | 477.84 | 476.15 | 462.14 | 634.86 |
| 24 | 487.50 | 485.78 | 471.49 | 647.70 |
How to use it
- Tap a preset scale (classical 650 mm, 25.5″, 24.75″, 25″, 34″ bass, ukuleles) or type your own, switching between inches and millimeters next to the field.
- Set the number of frets. The table and the summary update as you type.
- Pick the string type under Saddle compensation to see the usual range the saddle sits past the nominal scale.
- Choose the paper and tap Print template. In the print dialog, keep the scale at 100% (turn off "fit to page") and measure the 100 mm bar.
- Trim on the dashed splice line, overlap the gray strip and tape: the fret lines must line up.
Help and explanations
The template prints at full size on Letter or A4 paper, with a splice line and a 100 mm check bar so you can confirm the printout with a ruler before you cut a single slot. Everything runs in your browser, free, with no sign-up.
The fret formula
Each fret shortens the string just enough to raise it one semitone, and an equal-tempered semitone is the ratio 2^(1/12) ≈ 1.05946. So the distance from the nut to fret n is d = L − L ÷ 2^(n/12), where L is the scale length. The old 17.817 rule (each fret space is 1/17.817 of the remaining string) is the same math, rounded; the rule of 18, used into the 19th century, leaves the upper frets flat.
The numbers match the table published by luthier R. M. Mottola (liutaiomottola.com) and the StewMac fret calculator. The math doesn't depend on wood, fret wire or string count, only on the scale length.
Common scale lengths
Fender-style guitars use 25.5″ (647.7 mm) and Gibson-style guitars 24.75″ (628.65 mm); the 25″ (635 mm) middle ground is common on PRS and many modern guitars. Steel-string acoustics run from 24.75″ to 25.4″, a classical guitar is 650 mm (some smaller models 630 or 640 mm), and a standard electric bass is 34″ (863.6 mm), often 35″ on five-strings. Ukuleles are about 13″ soprano, 15″ concert and 17″ tenor.
To rebuild a neck, measure the real scale: double the distance from the nut to the 12th fret. Measuring to the saddle misleads you, since it is already compensated.
Saddle compensation
When you fret a string it stretches slightly and goes sharp. To make up for it, the saddle sits a little past the nominal scale, more on wound strings than on plain ones. The calculator shows a starting range by string type (for example 1.5 to 3 mm, roughly 1/16″ to 1/8″, on nylon and 3 to 6 mm on bass) as an estimate: the right value depends on action, gauge and fret height.
The final setting comes from the octave: the note fretted at the 12th must sound exactly one octave above the open string. Once the instrument is strung up, the intonation checker measures that string by string through the microphone.
Tips
- Always mark every fret from the nut, never by adding up fret-to-fret spacings: small ruler errors pile up.
- Before you cut, measure the printed 100 mm bar. If it reads 97 or 103 mm, the printer rescaled the page and the template is useless.
- To tune the finished instrument precisely, use the strobe tuner, which shows deviations of a tenth of a cent.
Frequently asked questions
How do you calculate fret positions?
Use d = L − L ÷ 2^(n/12), where L is the scale length and n the fret number. For 25.5″: 1st fret 1.431″, 5th 6.397″, 7th 8.481″ and 12th 12.750″ from the nut. For a 650 mm classical: 36.48, 163.05, 216.18 and 325 mm.
What is the 17.817 rule?
It's the same formula written as a division: the distance to the next fret is the remaining string length divided by 17.817. The number comes from 1 ÷ (1 − 2^(−1/12)). Rounding it to 18, as builders once did, makes the upper frets play flat.
What scale length is my guitar?
Most Fender-style guitars are 25.5″ (647.7 mm), Gibson-style 24.75″ (628.65 mm), PRS 25″ and classical guitars 650 mm. To check yours, measure from the nut to the 12th fret and double it.
Where is the 12th fret on a 24.75″ scale?
At 12.375″ (314.3 mm) from the nut, half the scale. The 1st fret is at 1.389″ and the 22nd at 17.805″.
Does the template print at full size?
Yes, as long as you print at 100%. Every sheet has a 100 mm check bar: measure it with a ruler before use. If the scale doesn't fit on one sheet, the template is split with a splice line and an overlap strip.
How much saddle compensation do I need?
As a starting point, 1.5 to 3 mm past the scale on nylon, 2 to 4.5 mm on a steel-string acoustic and 3 to 6 mm on bass, more on the bass side. It's an estimate: you finish it by setting the octave at the 12th fret.