Diminished (dim, °, dim7, °7) and Half Diminished (m7b5, -7b5, )

Difference

The difference between a diminished chord and a half diminished chord lies in the seventh.

  • The half diminished chord (m7b5) has a minor seventh (7) - it's a m7 chord wth a flat five (b5).
  • The diminished chord has a diminished seventh (dim7, °7). The minor 7th is again decreased by a semitone and hence is equivalent to a sixth (6) - only the theoretical approach is different.

Common Ground

Both are based on a diminished triad. This triad consists of two stacked minor thirds and thus represents a minor triad with a diminished fifth b5* (remember: the minor triad consists of a stack of minor third + major third, which together gives a perfect fifth).

*) You might consider writing mb5 as chord symbol instead of dim or °. However, this is uncommon.

Practically the diminished chord comes hardly ever as a pure triad.
dim (°) usually means dim7 (°7).

Chord shapes

Drag the slider under the chord shape to the right to change each half diminished chord to a diminished chord.

The minor 7th of C is a Bb. It's up to you if you prefer thinking or writin an A instead.

It's similar with Cb or Fb. In daily life you may sometimes just say "B" or "E".

The diminished 7th chord is completely symetric. It can be seen as a stack of minor thirds. That means that C°7, Eb°7, Gb°7 and A°7 are made of the same tones!

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