How to Write Seventh-Chord Symbols

In this installment of our chord series we look at how to write chord symbols for four-note chords. Earlier we covered triad notation; now we build on that foundation.

For further study, follow the related lessons about each seventh-chord type.

We have introduced six types of seventh chords. Review any unfamiliar type before moving on.

1. Dominant seventh.

2. Minor seventh.

3. Major seventh.

4. Minor-major seventh.

5. Half-diminished seventh.

6. Diminished seventh.

These six chords have different spellings and symbols. Use the related lessons to review their construction.

Now let us see how each symbol is written, taking C as the root.

First, the dominant seventh is based on a C major triad.

1. Dominant seventh: C7.

Add the number 7 to C. This indicates a major triad with a minor seventh.

Next, start with the C minor triad.

2. Minor seventh: Cm7.

Add 7 to Cm to obtain the minor-seventh symbol.

The major seventh is built on a C major triad.

3. Major seventh: Cmaj7, CM7 or C△7.

You will encounter all three spellings. They represent the same chord and depend on the writer’s convention. Learn to recognize each one. Importantly, uppercase M indicates major; lowercase m indicates minor.

Next is the minor-major seventh, built on Cm.

4. Minor-major seventh: Cm(maj7), CmM7 or Cm△7.

Combine a minor triad (Cm) with the major-seventh indication. See the earlier lesson on this chord for the notes.

The half-diminished seventh is based on a minor seventh with a lowered fifth.

5. Half-diminished seventh: Cm7♭5 or Cø7.

The ♭5 lowers the fifth of Cm7 by a semitone. The slashed-circle symbol ø means “half-diminished”; Cø7 has the same notes as Cm7♭5. Some charts shorten it to Cø.

Finally, the fully diminished seventh is built on a diminished triad.

6. Diminished seventh: Cdim7 or C°7.

Add 7 to Cdim or C°. That is all you need to recognize these common seventh-chord symbols.