About Chordfolk

How notes are spelled

Every scale and chord is stored as a degree formula, such as 1 b3 4 5 b7, and not as a list of steps. Steps cannot spell notes correctly: F# major has to contain E#, not F.

To spell a note, Chordfolk takes the letter that is the right number of steps above the root's letter, then adds the sharp or flat that makes the pitch come out right. The notes inside a scale are always spelled this way, so D major has F# and F major has Bb.

If a note would need more than a double sharp or double flat, Chordfolk does not respell it quietly. It tells you, and suggests an enharmonic root to try instead.

How modes are found

A mode is a parent scale started from a different degree. D dorian uses the same notes as C major, but D is home.

Chordfolk derives every mode by rotation. It starts the parent's pattern at the mode's degree, measures each note from the new root, writes the result as a degree formula, and spells it with the normal rules. No mode formula is typed by hand.

A parent is named by a standard key, so Db locrian is mode 7 of D major, and C# lydian is mode 4 of Ab major.

How CAGED shapes are placed

Each CAGED shape is anchored where the root falls in the matching open-chord shape. Take r as the fret of the root on the shape's anchor string. The C shape covers frets r-3 to r, with its anchor on string 5. The A shape covers r-1 to r+3 on string 5, the G shape r-3 to r+1 on string 6, the E shape r-1 to r+2 on string 6, and the D shape r-1 to r+3 on string 4.

The windows are defined on major keys, and every scale note inside a window belongs to that shape. Along the neck the five windows repeat in the order C, A, G, E, D.

Every 7-note scale uses the windows of a reference major key. The major and natural minor systems use the parent major key (A natural minor uses C major). Harmonic minor uses the relative major of its parent (A harmonic minor uses C major), and melodic minor uses the parallel major (A melodic minor uses A major).

In harmonic minor the 7th rises one fret from the reference key's note, and in melodic minor the 3rd drops one fret. A moved note stays on its string unless that puts it more than one fret outside the window, and then it moves to the neighboring string. The panel names the reference key when it differs from the root.

CAGED needs strings tuned in fourths with a major third between strings 3 and 2, so it is offered only for tunings with that pattern.

How boxes and three-note-per-string patterns are built

Boxes (for pentatonic and blues scales) and three-notes-per-string patterns (for 7-note scales and some others) are built the same way. Pattern k starts on scale note k on the lowest string, at the lowest fret where that note occurs.

From there Chordfolk takes the next two scale notes on that string (three for 3NPS), moves to the next string, continues with the next scale note at the fret where that pitch sits, and repeats up to the highest string. It uses absolute pitch from the tuning, so this works in any tuning.

Boxes and 3NPS positions are numbered by the scale note they start on, not by place on the neck, so box 5 can sit below box 1. Every pattern sits at the lowest spot on the neck where no fret is below 0.

How fingers are suggested

Suggested fingers are computed for every position and never stored. Open strings get finger 0. The home window is the four frets starting at the pattern's lowest fretted note, with one finger per fret from index (1) to pinky (4).

For each string, Chordfolk uses the four-fret window closest to home that holds all of that string's notes. A string that needs a different window is marked as a shift. If a string's notes span five frets, it uses fingers 1, 2, and 4, and marks the pinky note as a stretch.

Shifts and stretches are drawn with a dashed outline, so you can see where the hand moves.

How chord shapes are chosen

Theory gives a chord's notes, but not which fingering is sensible. Chordfolk lists up to three shapes for a chord. It starts with curated shapes: the familiar open chords, and the E-shape and A-shape barre forms on every root. They are listed with the open shape first, then the barre forms from the lowest fret up, and they apply in standard tuning.

For any other chord or tuning, Chordfolk searches the neck. It tries each four-fret window, with each string muted, open, or fretted on a chord tone. A shape must include every chord tone except the ones that quality lets you omit, such as the 5th of a 7 chord, and must sound at least three strings with at most four fingers. For a slash chord the bass note is the lowest sounding note.

The remaining candidates are ranked: the root in the bass, muted strings only at the bass end, lower positions, fewer fingers, and a smaller span. The top three are shown. If none qualifies, Chordfolk shows the chord's tones instead and says no playable voicing was found.