Major Seventh Chord

A major seventh chord is a major triad with a major seventh added above the root. On C it is C–E–G–B, written Cmaj7. Counting half steps from the bottom, it is 4 + 3 + 4. The seventh sits just one half step below the octave, and that gentle rub gives the chord its soft, glowing sound: richer than a plain major triad, but without the urge to move that a dominant seventh chord has.

Symbols

You will see Cmaj7, CM7, CΔ7 or just CΔ; the triangle means "major seventh". In Roman numeral analysis it is usually written I7 or IV7, with the key supplying the quality; some books, and most jazz analysis, write Imaj7 or IΔ7 to make it explicit.

Where it lives in a key

In a major key, the seventh chords on degrees 1 and 4 are major sevenths: Cmaj7 and Fmaj7 in C major. Alternating them makes one of the gentlest two-chord loops there is, because in the right hand only two notes move, each by a step.

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In a natural minor key the major sevenths fall on III and VI: in A minor, those are Cmaj7 and Fmaj7 again.

The seventh: B, not B♭

The most common slip is reading C7 as "C with a seventh". C7 is the dominant seventh, with B♭. For B♮ the symbol has to say maj7 (or M7, or Δ). The "maj" belongs to the seventh, not to the triad: a minor triad with a major seventh is written Cm(maj7).

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How it is used

In Baroque and Classical music, the seventh of I7 or IV7 is treated like any other dissonance, usually prepared in the previous chord and resolved down by step. In jazz, bossa nova, soul and a great deal of pop it is a stable color, and a song can end on it. When you voice it at the piano, many players avoid putting the root a half step (or a minor ninth) above the seventh, B4 with C5 for example, because that rub sounds harsher than the chord needs. Leaving the root to the bass, as in the examples here, keeps the sound smooth.

Practice with The major 7th and Name the seventh chords.