Chords & Harmony

Seventh Chord

Definition

A seventh chord is a four-note chord: a triad with one more third stacked on top, so the highest note is a seventh above the root. G–B–D–F (G7) and C–E–G–B (Cmaj7) are seventh chords.

A seventh chord is a triad with one more note stacked a third above its fifth. That new note is a seventh above the root, which gives the chord its name. G–B–D–F is a seventh chord on G (G7); C–E–G–B is one on C (Cmaj7). With four notes instead of three, seventh chords sound richer than triads, and most of them carry a little tension that wants to move on.

The five common types

Each type combines a triad quality with a seventh of a particular size. Counting half steps from the bottom:

Major seventh (Cmaj7, C–E–G–B): major triad + major seventh. 4 + 3 + 4.
Dominant seventh (C7, C–E–G–B♭): major triad + minor seventh. 4 + 3 + 3.
Minor seventh (Cm7, C–E♭–G–B♭): minor triad + minor seventh. 3 + 4 + 3.
Half-diminished seventh (Cø7 or Cm7♭5, C–E♭–G♭–B♭): diminished triad + minor seventh. 3 + 3 + 4.
Diminished seventh (C°7, C–E♭–G♭–B𝄫): diminished triad + diminished seventh. 3 + 3 + 3.

Treble staff in 4/4 with five whole-note seventh chords on C4: C E G B labeled Cmaj7; C E G B-flat labeled C7; C E-flat G B-flat labeled Cm7; C E-flat G-flat B-flat labeled Cm7-flat-5; C E-flat G-flat B-double-flat labeled Cdim7. Below: 4+3+4, 4+3+3, 3+4+3, 3+3+4, 3+3+3. — Cmaj7, C7, Cm7, Cm7♭5 (half-diminished) and Cdim7, with the half steps between neighboring notes below each chord. The root stays C; the third, fifth and seventh change.

Notice the double flat in the last chord. The seventh has to be some kind of B so that the chord stays a stack of thirds; B𝄫 is played on the same key as A.

Seventh chords in a major key

Add the scale's own seventh to each triad of a major key and you get a fixed pattern: major sevenths on I and IV, minor sevenths on ii, iii and vi, a dominant seventh on V and a half-diminished seventh on vii. In C major that gives Cmaj7, Dm7, Em7, Fmaj7, G7, Am7 and Bø7. Only one chord in the key is a dominant seventh, the one on the dominant, which is how that type got its name.

Treble staff in 4/4, four bars of half-note seventh chords rising on the C major scale, labeled Cmaj7, Dm7, Em7, Fmaj7, G7, Am7, Bm7-flat-5 and Cmaj7, with Roman numerals I7, ii7, iii7, IV7, V7, vi7, vii half-diminished 7 and I7 below. — A seventh chord on every degree of C major: Cmaj7, Dm7, Em7, Fmaj7, G7, Am7, Bm7♭5 and Cmaj7 again. The Roman numerals add a 7 to each; the key decides the quality.

In Roman numerals the 7 simply means "seventh chord"; the quality comes from the key. So I7 in C major is Cmaj7, not C7.

How seventh chords are used

In classical harmony the seventh is a dissonance that usually resolves down by step: when G7 moves to C, F falls to E. The dominant seventh chord is by far the most common; ii7 and the seventh chords on the leading tone are also frequent. In jazz, seventh chords are the basic vocabulary, and the ii–V–I progression (Dm7–G7–Cmaj7) is its most familiar progression. Because they have four notes, seventh chords have three inversions.

G7, the dominant seventh chord of C major: G, B, D and F.

Practice naming them with Name the seventh chords, and hear the difference with Hear the Seventh Chord: maj7, 7 or m7?

Common questions

How many types of seventh chords are there?

Five are common: major seventh, dominant seventh, minor seventh, half-diminished seventh and diminished seventh. Rarer types include the minor-major seventh, Cm(maj7), and the augmented seventh, C+7.

What is the difference between C7 and Cmaj7?

C7 is a dominant seventh chord: C–E–G–B♭, with a minor seventh on top. Cmaj7 is a major seventh chord: C–E–G–B, with a major seventh one half step higher.