Any chord, on both instruments at once.
Pick a root and a quality. You get the notes, the formula, where it sits on a keyboard, and every place it appears on a fretboard.
Root
Quality
C major
Keyboard
This chord belongs to these keys
Fretboard — every position in 12 frets
● root ● other chord tones
What this is actually showing you
Chords are stacked intervals, nothing more
Every chord here is built by counting semitones up from the root. The formula is the chord — the shapes on your instrument are just consequences of where those notes happen to sit.
01
Same chord, many places
On guitar the same three notes appear a dozen times across the neck. That is why one shape slides to twelve keys.
02
Major and minor differ by one note
Flatten the middle note by a semitone and major becomes minor. Toggle between them and watch which key moves.
03
Chords belong to keys
Most chords sit inside several keys at once. That overlap is what makes changing key possible.
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