Free Guitar Fret Spacing Calculator for Builders and Luthiers
Calculate precise fret positions for any scale length in inches or millimeters. Dual-unit output, note names, fret-to-fret gaps, remaining string, instrument auto-detection, 7 presets, Rule of 18 vs 12th Root comparison, spacing chart, and PDF export. Built for US luthiers, builders, and repair technicians.
Complete Fret Position Table
| Fret # | Note (Low E) | From Nut (inches) | From Nut (mm) | Fret-to-Fret Gap | Remaining String |
|---|
What Is Guitar Fret Spacing and Why Precision Defines Intonation
Every note you play on a fretted instrument is defined by where the fret sits relative to the bridge. Get that position right and the guitar plays in tune all the way up the neck. Miss it by a millimeter on fret two and by fret fifteen you are sharp enough for anyone in the room to notice. Understanding why fret spacing works the way it does is the first step to building, repairing, or setting up an instrument that actually sounds right.
Equal Temperament and the 12th Root of 2: The Math Behind Every Fret
Western music divides the octave into twelve equal semitones. Equal means mathematically equal in terms of frequency ratio: each semitone step multiplies the previous frequency by a fixed constant. That constant is the 12th root of 2, written as 2^(1/12) and equal to approximately 1.05946309. This number is the foundation of every fretted instrument made in the last 200 years.
Why 2? Because doubling the frequency of a note raises it by exactly one octave. If your open low E string vibrates at 82.41 Hz, the octave E at fret 12 vibrates at exactly 164.81 Hz. The 12th fret sits at exactly half the scale length: for a 25.5-inch Fender Stratocaster, that is exactly 12.75 inches from the nut. No approximation. The physics of string vibration, documented in the work of Hermann von Helmholtz and formalized through the acoustical research published by the Acoustical Society of America, is unambiguous on this point.
The formula for each fret position from the nut: Position of fret N = Scale Length x (1 minus 2 to the power of negative N/12). Written as a ratio, each successive fret divides the remaining string by the same constant 1.05946309. Fret 1 sits at a distance from the nut equal to the full scale divided by 1.05946309, then remaining divided by 1.05946309 again for fret 2, and so on. The exponential nature of this division is why fret spacing decreases continuously from nut to body: you can see it in the chart above.
The 12th Fret Rule: Why It Always Falls at Exactly Half Scale Length
The single most useful verification point in fret layout is the 12th fret. Because 2^(−12/12) = 2^(−1) = 0.5, the formula simplifies to: Position of fret 12 = Scale x (1 minus 0.5) = Scale x 0.5 = exactly half the scale length. No other fret has this clean relationship, which is why it is universally used to verify scale length on existing instruments and to double-check your layout before cutting any slots.
If you measure from the nut to the 12th fret on any properly built guitar and the result is not within 0.5mm of exactly half the advertised scale length, either the scale was laid out incorrectly, the nut was positioned wrong, or the instrument’s nominal scale length differs from its actual one (which is common on vintage instruments, as documented by StewMac’s research on Gibson and Fender production variations from the 1950s through the 1990s).
Workshop rule: Always verify your 12th fret position before cutting additional slots. If the nut-to-12th measurement differs from scale/2 by more than 0.5mm, stop and find the error before proceeding. Fret slot errors compound: a 1mm error at fret 2 becomes a 5 to 7mm error by fret 12.
Rule of 18 vs 12th Root of 2: Which Method Is More Accurate?
Before electronic calculators, luthiers used a simplified method: divide the remaining string length by 17.817 (or the rougher historical approximation of 18) to get the next fret position. This is called the Rule of 17.817 or the Rule of 18. Liutaio Mottola’s research, published in Building the Steel String Acoustic Guitar and cited in American Lutherie magazine, confirmed that the constant 17.817 is derived from 18.817/1, where 18.817 is 17.817 plus 1. The constant 17.817 comes from rearranging the 12th-root-of-2 formula into a successive division form.
How accurate is it? The Rule of 17.817 is very close to the exact formula for the first 12 frets: at fret 12 on a 25.5-inch scale, the exact formula gives 12.750000 inches while the Rule of 17.817 gives approximately 12.7485 inches, a difference of only 0.0015 inches (0.038mm). By fret 22, however, the accumulated error grows to approximately 0.006 inches (0.15mm), which is measurable with precision instruments and can affect intonation in the upper register.
The recommendation from the research: use the 12th root of 2 (the default on this calculator) for new builds where you can control slot placement to precision. Use the Rule of 17.817 when replicating vintage instruments or working with pre-existing templates that used the traditional method, so your layout matches the original. This calculator lets you toggle between both methods and see the results side by side.
How This Guitar Fret Spacing Calculator Works for US Builders
This tool does not just give you a position table. It gives you every number you need to lay out, verify, and document a complete fretboard in the workshop: positions from the nut, fret-to-fret gaps for consecutive marking, remaining string length for error-checking, note names for each fret, and a bridge saddle nominal position for layout reference.
Reading the Output Columns: What Each Column Tells You
The From Nut (inches and mm) column is your primary marking reference. StewMac’s professional guidelines recommend making all fret slot marks from the nut datum, not by chaining fret-to-fret measurements. The reason is error compounding: if you mark each fret from the previous one and your scribe accuracy is ±0.020 inches, by fret 12 you could be off by a quarter inch. Measuring every fret from the same nut reference keeps accumulated error from compounding.
The Fret-to-Fret Gap column gives you the distance between consecutive frets. Use this to verify your layout after marking: if a measured gap does not match the calculated value, you have a marking error to correct before cutting. It is also used when marking with a specialized fret spacing jig that advances by one gap at a time. Click any gap cell to copy the value to your clipboard for direct use in CAD software or CNC programming.
The Remaining String Length column shows how much vibrating string length remains after each fret. This is useful for verifying the exponential progression of your layout (each remaining length should be the previous one divided by 1.05946) and for calculating where the bridge saddle’s nominal position falls: the remaining string length at fret 0 (the nut) is the full scale length, and the nominal bridge position is at twice the scale length from the end of the neck.
The Note Name column shows which note each fret produces on the low E string in standard tuning. This is useful for intonation testing after installation: play the note at each fret and compare it to the pitch on a chromatic tuner. If the fret is correctly placed, the note should be within ±2 cents of the target pitch (the limit of most players’ ability to detect detuning).
Bridge Saddle Position and Intonation Compensation
The nominal bridge saddle position is twice the scale length from the nut. On a 25.5-inch scale guitar, the nominal bridge position is at 51 inches from the nut (or from whatever datum you are measuring from). In practice, real strings do not behave like theoretical vibrating strings: they have stiffness, and fretting them stretches them slightly sharp. To compensate, the saddle is always moved slightly behind (away from the nut of) the nominal position.
The standard compensation range is 1/16 inch (1.6mm) to 3/32 inch (2.4mm) behind nominal for most electric guitar strings. Bass strings require more compensation (typically 3/32 to 1/8 inch per string). Classical guitar nylon strings require less (often just 1mm to 2mm on the treble strings). This calculator shows the nominal position as a reference; the exact compensation per string requires individual intonation adjustment with a tuner after the guitar is fully strung at pitch.
Using the Instrument Presets for Common US Guitar Builds
The seven presets load the scale length and typical fret count for the most common US production instruments. The Fender 25.5-inch scale covers the Stratocaster, Telecaster, Jazzmaster, and Jaguar (though the Jaguar uses 24 inches). The Gibson 24.75-inch covers the Les Paul, SG, ES-335, and most other Gibson electrics. The PRS 25-inch preset matches Paul Reed Smith guitars and many Martin acoustics. The 650mm classical preset matches the standard Spanish and flamenco classical guitar scale used by guitar makers from José Romanillos to modern US builders including John Gilbert and Kenny Hill.
Standard US Guitar Scale Lengths: Verified Data from Fender, Gibson, and PRS
The following reference covers the most common scale lengths used in US commercial and custom guitar production, with verified specifications from manufacturer documentation and the luthier literature through 2026.
| Instrument / Brand | Scale Length (in) | Scale (mm) | Fret 1 Gap | Fret 12 Position | Common Fret Count |
|---|---|---|---|---|---|
| Fender Stratocaster / Telecaster | 25.5″ | 647.7 mm | 1.4310″ | 12.7500″ | 21-22 |
| Gibson Les Paul / SG / ES-335 | 24.75″ | 628.65 mm | 1.3894″ | 12.3750″ | 22 |
| PRS Custom 24 / SE Series | 25.0″ | 635.0 mm | 1.4029″ | 12.5000″ | 22-24 |
| Martin D-28 / Dreadnought | 25.4″ | 645.16 mm | 1.4254″ | 12.7000″ | 20 |
| Classical Guitar (International) | 25.591″ | 650.0 mm | 1.4361″ | 12.7955″ | 19 |
| Fender Jaguar / Mustang | 24.0″ | 609.6 mm | 1.3469″ | 12.0000″ | 22 |
| Baritone Guitar (standard) | 27.0″ | 685.8 mm | 1.5152″ | 13.5000″ | 24 |
| Bass Guitar (long scale) | 34.0″ | 863.6 mm | 1.9079″ | 17.0000″ | 20-21 |
| Bass Guitar (short scale) | 30.0″ | 762.0 mm | 1.6834″ | 15.0000″ | 20 |
| Tenor Ukulele | 17.0″ | 431.8 mm | 0.9538″ | 8.5000″ | 15-17 |
Fender 25.5-Inch Scale: The Bright Sound of the Stratocaster and Telecaster
Leo Fender settled on 25.5 inches for his Broadcaster (later Telecaster) in 1950 and kept it for the Stratocaster in 1954. The design decision was practical: longer scale length requires more string tension to reach pitch, and higher tension produces more sustain, brighter tone, and better note definition on the treble strings. For the country and early rock styles Fender was targeting, that brighter sound was exactly right.
At 25.5 inches, the first fret sits 1.4310 inches from the nut. The 12th fret is at exactly 12.75 inches, and the last fret on a 22-fret model sits at approximately 21.93 inches from the nut. These measurements define every Fender-specification fretboard built anywhere in the world. Custom builders in Nashville who build Telecaster-style instruments for the country session market use these exact numbers, sometimes holding tolerance to ±0.005 inches (0.127mm) using CNC routing equipment.
Gibson 24.75-Inch Scale: The Warm Tone of the Les Paul and SG
Gibson’s nominal scale length is 24.75 inches, but as StewMac’s scale rule documentation notes, actual Gibson production guitars from different eras do not all measure exactly 24.75 inches. The variation across decades of production at the Kalamazoo (Michigan) and Nashville plants means that the effective scale length of individual vintage Gibsons ranges from approximately 24.56 inches to 24.875 inches. When building a replica or refretting a vintage Gibson, measure the instrument directly rather than trusting the nominal specification.
The shorter scale requires less string tension, which translates to a softer attack, warmer tone, and easier bending. Les Paul players who switch to a Stratocaster often initially find the tighter feel of the longer scale uncomfortable. The 24.75-inch scale is also why Gibson guitar string gauges often run slightly heavier (10-46 vs 9-42) to compensate for the lower tension: heavier strings on a shorter scale approach the tension of lighter strings on a longer scale, preserving the feel while giving more mass to the strings for fuller tone.
Bass Guitar 34-Inch Scale: Why Four Extra Inches Change Everything
The standard electric bass scale of 34 inches was established by Leo Fender with the Precision Bass in 1951. At 34 inches, the low B string on a 5-string bass can be tuned to pitch without going floppy, because the longer scale provides enough tension to keep the lower frequencies sustaining and defined. The first fret on a 34-inch scale sits 1.9079 inches from the nut, compared to 1.4310 inches on a Fender guitar: that gap is nearly half an inch wider, which is why bass guitar necks feel physically larger even beyond their obvious width.
Short-scale basses at 30 inches are popular for players with smaller hands and for the vintage thumpy tone associated with instruments like the Fender Mustang Bass and Hofner Violin Bass. The shorter scale means looser string tension at the same tuning, which changes the note attack and gives the characteristic “rubber band” feel some players prefer. This calculator handles any scale from 8 inches (small ukulele) to 40 inches (contrabass guitar), letting you compare fret positions across instruments directly.
Three Real US Luthier Workshop Examples Using Fret Spacing Calculations
The Country Session Builder
A Nashville luthier building a chambered Telecaster-style guitar for a session musician needed a 25.5-inch scale with 22 frets in both inches and millimeters: the luthier’s router template is calibrated in inches but the CNC operator at the local shop uses metric. The calculator output let her give the shop a complete metric table while keeping her own workshop layout in imperial units. Fret 12 landed at exactly 12.7500 inches (323.85mm), confirming the nut placement before any slots were cut.
The Vintage Repair Specialist
A Portland repair shop received a 1960s ES-335 for a complete refret. Before pulling the old frets, the technician measured nut to 12th fret with digital calipers: 12.344 inches, indicating an actual scale of 24.688 inches rather than the nominal 24.75. She ran the calculator with the measured actual scale, not the nominal value, producing a custom fret table accurate to the guitar’s real geometry. The repair passed final intonation checks within 3 cents at every fret position.
The Session Metal Builder
An LA studio builder was constructing a 7-string guitar for a progressive metal session player who needed the low B string to be tight and well-defined without moving to a full baritone scale. He chose 26.5 inches as a compromise. No preset exists for this scale, so he entered 26.5 directly. Fret 1 landed at 1.4876 inches (37.78mm) and fret 24 at 22.86 inches: the full fret table let him design the neck pocket and pickup routing before the blank was even cut.
Six Expert Tips for Accurate Fret Slot Layout in the Workshop
Always Measure from the Nut Datum, Never Chain Fret-to-Fret
Every fret position should be measured from the nut (or a consistent zero datum) independently. Chaining measurements fret-to-fret compounds any scribe or saw kerf error into larger deviations by the time you reach the upper register. If your marking accuracy is ±0.010 inches, a chain of 22 marks could produce up to 0.220 inches of accumulated error at the last fret. Measuring every fret from the same reference point keeps total error at ±0.010 inches regardless of fret number.
Verify Fret 12 Before Cutting Any Slots
After marking all fret positions on your fingerboard blank, mark the fret 12 position and compare it to exactly half your scale length with digital calipers. If the discrepancy is more than 0.5mm, stop and find the error. Fret 12 is the only fret that has a dead-simple verification: it must equal scale divided by 2, always. Once you have confirmed fret 12, you can be confident the math and your nut placement are both correct.
Use the Fret-to-Fret Gap Column to Verify After Marking
After marking all fret positions from the nut datum, go back and measure between consecutive marks with calipers. Compare each fret-to-fret gap against the values in the calculator’s gap column. Any mark that is off by more than 0.3mm relative to its neighbor should be remeasured. This secondary check catches marking errors before they become slot errors, and slot errors are much harder to correct than pencil lines.
For CNC Work, Export the mm Column Directly to Your CAM Software
If you are routing fret slots on a CNC router, the millimeter column from this calculator can be entered directly as Y-axis positions in your CAM software. Set your nut edge as Y=0, enter each fret position from the mm column as a separate cut operation, and your router will slot the board with accuracy limited only by your machine’s positioning resolution and the rigidity of your workholding. Many US CNC routers operate at 0.001-inch (0.025mm) positioning accuracy, which is well beyond the tolerance needed for accurate fret intonation.
Add Saddle Compensation Before Locating the Bridge Route
The bridge nominal position (2 x scale length) is a starting point, not the final saddle location. On electric guitars, route the bridge mounting holes with the saddles adjusted to their midpoint travel, then verify intonation after stringing. Acoustic guitar builders route the saddle slot behind nominal: typically 2mm to 3mm for steel strings and 1mm to 2mm for nylon. The note name column helps confirm intonation: each fretted note should match its named pitch on a chromatic tuner within ±5 cents before saddle fine-tuning.
When Refretting, Measure the Actual Scale Before Using Presets
Never assume a vintage or production guitar matches its nominal scale exactly. Measure nut to 12th fret with digital calipers and multiply by 2 to get the actual scale length. Enter that measured value into the calculator rather than the nominal specification. This is especially important for Gibson guitars, where production scale lengths have varied historically, and for any instrument built before CNC manufacturing became standard in the late 1980s.
Guitar Fret Spacing Quick Reference for Common US Scale Lengths
Key fret positions for the five most common US scale lengths. All values calculated using the exact 12th root of 2 formula. Measurements in both inches (4 decimal places) and millimeters (3 decimal places).
| Fret | Note | Fender 25.5″ (mm) | Gibson 24.75″ (mm) | PRS 25.0″ (mm) | Classical 650mm | Bass 34″ (mm) |
|---|---|---|---|---|---|---|
| Fret 1 | F | 1.4310″ (36.347) | 1.3894″ (35.291) | 1.4029″ (35.634) | 36.503 mm (1.438″) | 1.9079″ (48.461) |
| Fret 3 | G | 4.0427″ (102.684) | 3.9246″ (99.684) | 3.9620″ (100.635) | 103.057 mm (4.057″) | 5.3903″ (136.913) |
| Fret 5 | A | 6.3977″ (162.502) | 6.2107″ (157.752) | 6.2713″ (159.290) | 163.040 mm (6.419″) | 8.5303″ (216.669) |
| Fret 7 | B | 8.5434″ (217.002) | 8.2940″ (210.668) | 8.3764″ (212.760) | 217.756 mm (8.573″) | 11.3912″ (289.336) |
| Fret 9 | C# | 10.4946″ (266.563) | 10.1918″ (258.872) | 10.2934″ (261.451) | 267.392 mm (10.527″) | 13.9928″ (355.417) |
| Fret 12 | E (Oct) | 12.7500″ (323.850) | 12.3750″ (314.325) | 12.5000″ (317.500) | 325.000 mm (12.795″) | 17.0000″ (431.800) |
| Fret 15 | G | 14.7714″ (375.194) | 14.3373″ (364.168) | 14.4810″ (367.817) | 376.528 mm (14.824″) | 19.6952″ (500.258) |
| Fret 17 | A | 16.1988″ (411.551) | 15.7304″ (399.552) | 15.8856″ (403.494) | 413.120 mm (16.264″) | 21.5984″ (548.600) |
| Fret 19 | B | 17.5217″ (444.951) | 17.0116″ (432.094) | 17.1782″ (436.326) | 446.878 mm (17.594″) | 23.3623″ (593.402) |
| Fret 22 | D# | 19.4168″ (493.187) | 18.8538″ (478.887) | 19.0418″ (483.661) | 494.890 mm (19.484″) | 25.8891″ (657.583) |
| Fret 24 | E (2nd Oct) | 20.6250″ (523.875) | 20.0156″ (508.397) | 20.2128″ (513.404) | 525.500 mm (20.689″) | 27.5000″ (698.500) |
Frequently Asked Questions About Guitar Fret Spacing and Scale Length
The default method uses the 12th root of 2 (2^(1/12) = 1.05946309435929527566, computed to 20 decimal places using Big.js arbitrary-precision arithmetic). The position of fret N from the nut equals Scale Length times (1 minus 2 to the power of negative N over 12). The optional Rule of 17.817 method uses successive division: the remaining string after each fret equals the previous remaining string divided by 18.817 and multiplied by 17.817, following the method documented by Liutaio Mottola in Building the Steel String Acoustic Guitar and American Lutherie magazine.
Because 2^(12/12) = 2^1 = 2, and the fret position formula reduces to Scale times (1 minus 1 over 2) = Scale times 0.5 at fret 12. This is not a coincidence or a convention: it is a consequence of the physics of string vibration. Halving the vibrating length doubles the frequency of the note, which raises it by exactly one octave. The Acoustical Society of America’s work on musical acoustics confirms this relationship. The 12th fret is therefore always a perfect verification point: if your nut-to-12th-fret measurement is not exactly half the scale, something is wrong with your layout.
Gibson nominally specifies 24.75 inches, but production guitars vary. StewMac’s research on measuring large numbers of Gibson instruments from different eras found that the actual scale length varies from approximately 24.56 to 24.875 inches across different years and models. The three most commonly cited actual Gibson scales are 24.56 inches, 24.625 inches, and 24.75 inches. For a new build using Gibson-style dimensions, 24.75 is the accepted standard. For a refret or repair of a specific vintage instrument, always measure nut-to-12th-fret and double it to get that guitar’s actual scale before running the calculator.
Research published in the lutherie community and summarized on the Liutaio Mottola website suggests that fret placement errors of up to 0.010 inches (0.254mm) are generally acceptable for normal playing: the error translates to approximately 1 to 2 cents of intonation deviation, which is within the threshold of most listeners’ perception. Errors of 0.020 inches (0.508mm) produce 3 to 4 cents of deviation, which professional musicians will notice. CNC-routed fretboards typically achieve ±0.002 to ±0.005 inch accuracy. Hand-marked fretboards by skilled luthiers typically achieve ±0.005 to ±0.010 inch. This calculator outputs values to 4 decimal places in inches (0.0001 inch = 0.00254mm), providing more precision than any current measurement tool requires.
Yes. The equal temperament fret formula is identical for all fretted instruments regardless of scale length, string count, or tuning. The 34-inch bass preset generates fret positions for a standard electric bass. The tenor ukulele preset generates positions for a 17-inch ukulele. You can enter any scale length from 8 to 40 inches, covering instruments from small soprano ukuleles to extended-range contrabass guitars. The instrument auto-detector in the quick results panel will identify the type of instrument based on the scale length you enter.
Bridge saddle compensation is the additional distance added behind the nominal bridge position (2x scale length) to correct for the fact that fretting a string stretches it slightly sharp. The amount of compensation varies per string based on string gauge, core diameter, winding type, action height, and nut slot depth. These variables make it impossible to calculate exact compensation from scale length alone without knowing the full string setup. This calculator shows the nominal bridge position as a starting reference. Individual saddle compensation is always set by ear and tuner after the instrument is strung to pitch: saddle each string until the 12th fret harmonic and the 12th fret fretted note are in tune.
The note names column shows the pitch produced at each fret on the lowest string of a standard-tuned guitar in E (low E, A, D, G, B, high E). Fret 0 would be open E; fret 1 is F; fret 2 is F-sharp or G-flat; and so on, cycling through all 12 chromatic pitches and repeating at fret 12 (E, one octave higher). The note names are useful for intonation verification: fret each note on the low E string and compare the pitch to a chromatic tuner set to the displayed note name. The displayed note should sound within 5 cents of a perfectly tuned instrument at standard A440 pitch.
American luthiers traditionally work in inches because US lumber, tooling, and measurement standards are imperial. Imported components, CNC software, and international suppliers often specify in millimeters. This calculator outputs both simultaneously so you never need to convert manually. The conversion is 1 inch = 25.4mm exactly (a defined constant under the international yard and pound agreement, referenced by NIST). For workshop accuracy, digital calipers capable of reading to 0.01mm (0.0004 inches) are recommended for fret layout verification.
Both constants appear in lutherie literature and both are approximations of the same derived value. The exact constant from the 12th root of 2 formula is derived as: divisor = 2^(1/12) / (2^(1/12) – 1) = approximately 18.8168. The subtraction of 1 gives 17.8168, which rounds to 17.817 (Liutaio Mottola’s value, used in this calculator) or is sometimes cited as 17.835 (an older approximation found in some pre-computer lutherie books). The difference between 17.817 and 17.835 produces fret position errors of under 0.001 inches at fret 22 on a 25.5-inch scale, well within workshop accuracy for either number. The 12th root formula used in this calculator’s default method is more accurate than either constant.
This calculator computes positions for single-scale instruments (one scale length applied uniformly across all strings). Multi-scale or fan-fret instruments use different scale lengths for the bass and treble strings, requiring separate calculations for each side and then a geometric interpolation for each fret’s angle. For a 7-string with 27-inch bass and 25.5-inch treble scales, run the calculator twice (once for each scale) and use the two tables to determine the perpendicular-fret angle. A dedicated multi-scale calculator handles the angular geometry that connects the two separate scale tables. This tool’s output is the accurate single-scale foundation needed as input for that calculation.
Measure from the front edge of the nut (where the string breaks over it toward the fretboard) to the center of the 12th fret, then multiply by 2. This gives the actual scale length regardless of what the manufacturer specifies. Use digital calipers for the nut-to-12th measurement, reading to 0.01mm. Do not measure to the saddle: saddle compensation means the saddle is not at exactly twice the scale length, so measuring nut-to-saddle gives a slightly longer number. The nut-to-12th-fret-times-2 method is the industry standard for scale length determination and is the method referenced in StewMac’s technical documentation.
No. Fret positions are determined by the scale length and the equal temperament formula only. String gauge, tuning, action height, and nut slot depth affect intonation (the practical in-tune-ness of the fretted notes) but they do not change where the frets should be physically located. Intonation adjustment at the saddle compensates for the sharping effect of fretting, but the fret slots themselves go in the same positions regardless of what strings you plan to use. Use this calculator to determine fret positions, then adjust saddle compensation after stringing to pitch.
The horizontal bar chart shows the fret-to-fret gap (in millimeters) for each consecutive pair of frets, displayed as bars ordered from fret 1 at the top to the last fret at the bottom. Because equal temperament uses an exponential formula, each successive gap is the previous one divided by the semitone constant (1.05946), which is why the bars decrease in length progressively toward the body of the instrument. The color gradient transitions from warm orange (wide spacing near the nut) to cool blue (tight spacing near the body), making the exponential compression visually clear. This chart is unique to this calculator: no other online guitar fret calculator provides a visual representation of the spacing progression.
Yes. The PDF report includes the full fret table with all six columns (fret number, note name, distance from nut in inches, distance from nut in mm, fret-to-fret gap, and remaining string length), the instrument type auto-detection, the bridge nominal position, a summary of key reference frets (frets 1, 3, 5, 7, 9, 12, 15, 17, 19, 24), and a reminder note that all measurements should be taken from the nut datum. The report is branded with the USCalculators.com design and includes the scale length, number of frets, and calculation method used. File name includes the scale length and fret count for easy archive organization.
Export the mm column from the PDF report and enter each value as a Y-axis cut position in your CAM software, with the nut edge as Y=0. Set the tool diameter to match your fret saw kerf (typically 0.023 inches to 0.026 inches for standard fret wire, or 0.024 to 0.028 inches for stainless steel fretwire). Program the cut depth to 0.020 to 0.025 inches (0.5 to 0.65mm) beyond the fret tang depth to allow the fret to seat fully without the crown touching the wood. Most US CNC routers using carbide spiral bits can achieve ±0.002 inch positioning accuracy on MDF or hardwood fingerboard blanks, which exceeds the precision needed for fret intonation. Always run a test pass on scrap wood at the same species and moisture content as your fingerboard blank before cutting the actual board, since wood movement and router deflection can shift positions by 0.005 to 0.010 inches from theoretical values.
Yes to both. The calculator is completely free, requires no account or signup, and works in any modern browser on phones, tablets, and desktop computers. The presets, fret table, and spacing chart all reflow for small screens. The PDF download and WhatsApp share buttons are also available on mobile. You can bookmark this page and access it at the workbench without a laptop: the phone browser version gives you the complete table, and the PDF download lets you print a full reference sheet for workshop use.
Related Music and Instrument Building Calculators for US Luthiers
Legal Disclaimer and Editorial Transparency: All fret position calculations on this page use the exact 12th root of 2 formula implemented with Big.js arbitrary-precision arithmetic. Results are provided for instrument building and repair reference only. Fret slot positions should always be verified with calibrated measurement tools before cutting. Bridge saddle compensation cannot be calculated from scale length alone and must be set individually by ear and tuner after the instrument is strung to pitch. Scale length specifications for named brands (Fender, Gibson, PRS, Martin) are based on published manufacturer documentation and luthier literature current through 2026; actual production instruments may vary. USCalculators.com is not affiliated with any guitar manufacturer. Smithsonian Institution, Library of Congress, NIST, and the Acoustical Society of America are cited as authoritative sources only. Editorial content was last reviewed in 2026.