Seventh Chords are common and can be found in six main 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). In addition, there are alternate seventh chords.
See diagrams of seventh chords:
C7 D7 E7 F7 G7 A7 B7
See also graphic overview of dominant seventh chords in common keys ›
The seventh chords have in common that the seventh note of a scale is added to a triad (a three-note chord), making it a four-note chord (also called a tetrachord).
We can compare the different seventh chords with C as root note:
C7: C – E – G – Bb
Cm7: C – Eb – G – Bb
Cmaj7: C – E – G – B
The name "dominant" refers to the fifth degree of the diatonic scale. It is called dominant because it is most weighty besides the tonic (the root of the scale) and it's neither major nor minor. 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). A slight dissonance could be heard in 7th chords because the seventh note often creates tension that seeks resolution. Note that the fifth sometimes are omitted, especially when these chords are inverted.
Major 7th is constructed by adding the seventh tone in the scale to a major triad.
Minor 7th is constructed by adding a minor seventh tone in the scale to a minor triad. Similar to the 7th chord, a slight dissonance could be heard in minor 7th chords because one of the notes, the seventh, is not included in the same key as the root note.
How and when to use seventh chords? Seventh chords are common in many music styles, but especially in blues (major 7th not included) and jazz.
Chord sequences that show how 7th chords can be utilized:
1. C7 - F7 - C7 - G7 - F7 - C7
2. C7 - F7 - C7 - Dm7 - G7 - F7 - C7
3. C7 - F7 - C7 - A7 - Dm7 - G7 vC7
4. Dm7 - G7 - Cmaj7
(Typical blues and jazz progressions.)
Minor 7th flat 5 is built by taking a minor seventh chord and lowering the fifth (indicated by b5 in the chord name). This chord group is also known as half-diminished. It is commonly used in jazz and can function as the ii chord in ii-V-I progressions.
Here are the other three groups of seventh chords, with examples in the note of C:
Cdim7: C – Eb – Gb – A
Caug7: C – E – G# – A#
CmM7: C – Eb – G – B
There are other seventh chords such as 7b5 and 7#9. For more variations of seventh chords, see Altered chords. The seventh chord is related to the group of extended chords.
For more in-depth about music theory, see Chord Theory for Piano eBook.
Major chords Minor chords Seventh chords Extended chords Sus chords Dim chords Aug Chords Add Chords Altered Chords