Number System
Guitar Reference
Tonic (I, vi)
Subdominant (IV, ii)
Dominant (V, iii, vii°)
Key
Progression
1–4–5
1–5–6–4
1–4–6–5
6–4–1–5
2–5–1
1–6–4–5
1–5–4–5
Custom
–
–
–
Key
C major
Progression
1–5–6–4
Scale
C D E F G A B
Circle of Fifths
Progression in Key
Diatonic Chords
Chord Diagrams
Major Scale on Fretboard