C Major 6th
6
0 - 4 - 7 - 9Major + major 6th
About C Major 6th
C6 is a C major chord with an A added, and it is the sound of a song ending without ceremony. Where Cmaj7 lingers and C7 pushes onward, C6 simply stops — which is why swing bands, country players and early jazz guitarists used it as a final chord for decades.
The notes
C, E, G, A. The A is a major sixth above the root. It adds colour without adding tension: no tritone, no leading note, nothing that needs to move.
Read the same four notes from A and you get A minor seventh. The chords are identical on paper and differ only in which note the bass takes — an equivalence used constantly in arranging.
On the fretboard
The easiest version keeps the open C shape and adds the A on the G string at the second fret, or simply lets the open A string sound. Both work; the second is thinner and more open.
The tight swing voicing puts all four notes on adjacent strings in the middle of the neck, which is how rhythm guitar in that idiom is played — no open strings, everything muted the instant the chord changes.
Where it shows up
As a tonic substitute in C major, especially at the end of a piece. In older popular music the sixth was the default final chord; the major seventh replaced it later, and the two date a recording almost as reliably as its production.
It also appears mid-progression as a way to sit on the tonic without stalling — a bar of C followed by a bar of C6 moves without changing harmony.