What Is a Seventh Chord?
What Is a Seventh Chord?
A seventh chord is a triad with one more third stacked on top — four notes, the new one sitting a seventh above the root. That fourth note is where chords stop being plain and start having color: the dreaminess of maj7, the mellow melancholy of m7, the bluesy itch of 7.
The three you'll actually meet
| Chord | Formula | Sound | Example |
|---|---|---|---|
| Major seventh (Cmaj7) | 1 3 5 7 | soft, jazzy, floating | C E G B |
| Minor seventh (Cm7) | 1 ♭3 5 ♭7 | smooth, rounded minor | C E♭ G B♭ |
| Dominant seventh (C7) | 1 3 5 ♭7 | tense, bluesy, pulling | C E G B♭ |
Note the trap: C7 and Cmaj7 are different chords. The plain "7" means the flat seventh. The full tour — including m7♭5 and diminished sevenths — is in Seventh Chords Explained.
Sevenths in a key
Stack a fourth note on each diatonic chord and every major key yields the same quality map: Imaj7, iim7, iiim7, IVmaj7, V7, vim7, viim7♭5. That map is why jazz charts are wall-to-wall sevenths — they're just the key's native chords, fully spelled. On the fretboard, the shapes follow the same logic as triads with one added voice; How Chords Are Built from Scales shows the derivation.
Related terms
- Dominant seventh chord — the tension specialist
- Chord extension — stacking past the seventh
- Chord symbols — decoding maj7 vs 7 vs m7