Portuguese guitar fret calculator
The Portuguese guitar comes in two main models, and the difference starts with the scale. Fernandez Music gives about 440 mm for the Lisbon guitar and about 470 mm for the Coimbra guitar. The calculator opens at 440 mm with 21 frets: the 1st fret sits 24.70 mm from the nut, the 5th 110.37 mm, the 12th 220.00 mm and the 21st 309.19 mm.
Portuguese guitar fret positions, 440 mm Lisbon scale
Distance of each fret from the nut, from the previous fret and to the saddle on a 21-fret Lisbon guitar.
| Fret | From nut (mm) | From previous (mm) | To saddle (mm) |
|---|---|---|---|
| 1 | 24.70 | 24.70 | 415.30 |
| 2 | 48.00 | 23.31 | 392.00 |
| 3 | 70.01 | 22.00 | 369.99 |
| 4 | 90.77 | 20.77 | 349.23 |
| 5 | 110.37 | 19.60 | 329.63 |
| 6 | 128.87 | 18.50 | 311.13 |
| 7 | 146.34 | 17.46 | 293.66 |
| 8 | 162.82 | 16.48 | 277.18 |
| 9 | 178.37 | 15.56 | 261.63 |
| 10 | 193.06 | 14.68 | 246.94 |
| 11 | 206.92 | 13.86 | 233.08 |
| 12 | 220.00 | 13.08 | 220.00 |
| 13 | 232.35 | 12.35 | 207.65 |
| 14 | 244.00 | 11.65 | 196.00 |
| 15 | 255.00 | 11.00 | 185.00 |
| 16 | 265.39 | 10.38 | 174.61 |
| 17 | 275.19 | 9.80 | 164.81 |
| 18 | 284.44 | 9.25 | 155.56 |
| 19 | 293.17 | 8.73 | 146.83 |
| 20 | 301.41 | 8.24 | 138.59 |
| 21 | 309.19 | 7.78 | 130.81 |
Fernandez Music, Master Portuguese Guitars (Lisbon about 440 mm; Coimbra about 470 mm)
How to use it
- Tap Portuguese guitar 440 mm for a Lisbon model, or type 470 mm for Coimbra.
- The fret count starts at 21, as on the Carvalho LS305; shop listings range from 18 to 21, so change it to match yours.
- Keep the Short scale, steel compensation: light steel strings on a short scale need very little.
- Print at 100%, measure the 100 mm bar and tape the sheets on the splice line.
Help and explanations
For a Coimbra guitar, type 470 mm: the 1st fret moves to 26.38 mm and the 12th to 235.00 mm. Print the template at full size on Letter or A4 to mark or check a fretboard. Everything runs in your browser, free, with no sign-up.
Lisbon and Coimbra scales
Wikipedia gives 445 mm for the Lisbon guitar and 470 mm for the Coimbra guitar, and builders stay close to those figures: Thomann's Lisbon Deluxe measures 440 to 442 mm, the Larkin Lisbon fado guitar 17 3/8″ (441 mm) with 18 frets, and the Carvalho LS305 450 mm with 21 frets. Fernandez Music lists a Coimbra guitar at 472 mm.
The Coimbra guitar is also tuned a whole step lower, C G A D G A instead of D A B E A B, which suits its longer strings. On a 470 mm scale every fret sits about 7 % further from the nut than on a 440 mm Lisbon guitar.
Short scale, light steel
With twelve light steel strings, .009 to .036 in a Galli Lisbon set, the Portuguese guitar needs little saddle compensation. The calculator suggests 0.5 to 1.5 mm as a starting range, labeled as an estimate. The three bass courses are octave pairs, so the thick and thin strings of each course may want slightly different positions.
The 12th fret must land at exactly half the scale: 220.00 mm on a Lisbon guitar, 235.00 mm on a Coimbra. Check each string's octave with the intonation checker once strung.
Tips
- Mark every slot from the nut, never fret to fret: on a short scale, half a millimeter is audible.
- Measure your guitar before choosing Lisbon or Coimbra: some instruments fall in between, around 450 mm.
- Tune Lisbon or Coimbra with the Portuguese guitar tuner before you check intonation.
Frequently asked questions
What is the scale length of a Portuguese guitar?
About 440 to 450 mm for the Lisbon model (Wikipedia gives 445 mm) and about 470 mm for the Coimbra model. Measure yours from the nut to the 12th fret and double it.
What's the difference between a Coimbra and a Lisbon guitar?
The Coimbra guitar has a longer scale, about 470 mm against 440 to 450 mm, and is tuned a whole step lower (C G A D G A instead of D A B E A B). The two also differ in body and headstock design.
How many frets does a Portuguese guitar have?
Usually 18 to 21, depending on the model; the Larkin Lisbon guitar has 18 and the Carvalho LS305 has 21.
Where is the 12th fret on a Portuguese guitar?
At 220.00 mm from the nut on a 440 mm Lisbon guitar and at 235.00 mm on a 470 mm Coimbra guitar. The 17th fret is at 275.19 mm on the Lisbon model.
How many strings does a Portuguese guitar have?
Twelve steel strings in six double courses. The three bass courses are octave pairs; the three treble courses are in unison.