Seventh chords

Seventh Chords are common and can be found in six variants. The three most common are Dominant Seventh chords (7), Major Seventh chords (maj7) and Minor Seventh chords (m7). Three less common variants are Minor Major Seventh (mM7), Dim seventh (dim7), Augmented seventh (aug7).

See diagrams of seventh chords:

C7 D7 E7 F7 G7 A7 B7

Cmaj7 Dmaj7 Emaj7 Fmaj7 Gmaj7 Amaj7 Bmaj7

Cm7 Dm7 Em7 Fm7 Gm7 Am7 Bm7

Theory

The seventh chords have in common that the seventh note in a scale is added to a triad. We can compare the different seventh chords in the note of C:

C7: C – E – G – Bb
C7 chord

Cm7: C – Eb – G – Bb
Cm7 chord

Cmaj7: C – E – G – B
Cmaj7 chord

Dominant 7th

The name "dominant" refer to the fifth degree of the diatonic scale and it is called dominant because it is most weighty besides the tonic (the root of the scale). The most common dominant chord is a dominant seventh in which a minor seventh is added to a triad major. A less common alternative chord name for C7 is Cdom7 (dom stands for dominant). The seventh chord belongs also to the group of extended chords.

Minor 7th

Minor 7th is constructed by adding a minor seventh tone in the scale to a minor triad.

Major 7th

Major 7th is constructed by adding the seventh tone in the scale to a major triad.

Additional seventh chords

Here are the other three groups of seventh chords, with examples in the note of C:

Cdim7: C – Eb – Gb – A
Cdim7 chord

Caug7: C – E – G# – A#
Caug7 chord

CmM7: C – Eb – G – B
CmM7 chord

For more variations of seventh chords, see also Altered chords.