A minor seventh chord consists of four notes, all found within the natural minor scale. The chord formula is 1 b3 5 b7. Apply this formula to the major scale based on the desired root note.

For example, to create a C minor seventh chord, begin with the C major scale: C D E F G A B. Next, apply the formula, choosing the root, the flatted third, the fifth, and the flatted seventh. The resulting chord is spelled C Eb G Bb. This chord may be abbreviated as Cm7, C-7, or Cmin7.

Note that when only C7 is written, this indicates a dominant seventh chord, not a minor seventh.