Fretboard Geometry

The all-fourths fretboard is a uniform lattice where every geometric relationship between notes is consistent across the entire instrument. This section maps out the key patterns.

The Fundamental Principle

Each fret is one half step. Each string crossing is a perfect fourth (5 frets). Therefore, any two-dimensional shape on the fretboard represents a fixed intervallic relationship, regardless of where you place it. This is not true in standard tuning.

Interval Shapes (Same String vs. Adjacent Strings)

On the same string, intervals are measured in frets:

• Minor 2nd: 1 fret
• Major 2nd: 2 frets
• Minor 3rd: 3 frets
• Major 3rd: 4 frets
• Perfect 4th: 5 frets (= one string crossing)

Across adjacent strings (with fret offset):

• Perfect 4th: same fret, next string up
• Tritone: same fret +1, next string up
• Perfect 5th: same fret +2, next string up
• Minor 6th: same fret +3, next string up
• Major 3rd: same fret -1, next string up
• Minor 3rd: same fret -2, next string up

Octave Pattern

An octave is always 2 strings up, 2 frets toward the bridge. This is the most important shape in P4 tuning. It never changes. In standard tuning, octaves shift by one fret when crossing the G-B string pair; in P4, the shape is absolutely consistent.

Unison Pattern

The same pitch on an adjacent higher string is 5 frets lower (toward the nut). On a string two above, it is 10 frets lower (or equivalently, 2 frets higher).

Diagonal Tiling

Because the tuning is uniform, any pattern tiles diagonally across the fretboard. A pentatonic box at fret 5 on strings 6-5 appears identically at fret 10 on strings 4-3 and fret 15 on strings 2-1. Connecting these tiles gives you full-neck coverage from a single shape.

Symmetry Groups

Certain note collections have special symmetry on the P4 fretboard:

• Whole tone scale: Tiles perfectly in straight horizontal lines
• Diminished scale: Forms a rectangular grid pattern
• Chromatic scale: Every fret, every string — the complete lattice

Practical Implications

When learning new material, always ask: "What shape is this?" Once you identify the shape, you know it works everywhere. This is the P4 advantage distilled to one principle: learn shapes, not positions.