Half diminished chord (m7♭5): formula, notes and sound
A half diminished chord (m7♭5) is a diminished triad plus a minor seventh (0-3-6-10). Hear it, see it on every root, and learn its place in minor keys.
A half diminished chord (minor seven flat five, m7♭5 or ø7) is a diminished triad plus a minor seventh: 0, 3, 6, 10 semitones. Bm7♭5 is B, D, F and A; Cø7 is C, E flat, G flat and B flat. It sounds dark and yearning, less harsh than the fully diminished seventh.
Listen to Cm7♭5
C E♭ G♭ B♭
What is the formula of a half diminished chord?
| Chord tone | Interval from the root | Semitones | In C |
|---|---|---|---|
| Root | root | 0 | C |
| Third | minor third | 3 | E♭ |
| Fifth | diminished fifth | 6 | G♭ |
| Seventh | minor seventh | 10 | B♭ |
Formula: 0-3-6-10 semitones. Written Cm7♭5, Cø7, Cø.
What does a half diminished chord sound like?
Moody and searching, the classic sound of the ii chord in a minor key (ii ø7 – V7 – i).
How to recognise it by ear
- Think minor seventh with a darker, lowered fifth.
- It is the chord on the 7th degree of a major key (Bm7♭5 in C) and on the 2nd degree of a minor key (Bø7 in A minor).
- Compared with the diminished seventh, the top note is a semitone higher, so it sounds less symmetrical and less dramatic.
Quick test: is it a half diminished chord?
Four chords on different roots. Each is a half diminished chord or a chord it is often confused with.
Score: / 4 (your score updates as you answer)
Half diminished chords on all 12 roots
Spelled by letter from the formula, so thirds are always a letter apart (E♭, not D♯, in C minor).
| Chord | Notes | Hear it |
|---|---|---|
| Cm7♭5 | C E♭ G♭ B♭ | |
| C♯m7♭5 | C♯ E G B | |
| Dm7♭5 | D F A♭ C | |
| D♯m7♭5 | D♯ F♯ A C♯ | |
| Em7♭5 | E G B♭ D | |
| Fm7♭5 | F A♭ C♭ E♭ | |
| F♯m7♭5 | F♯ A C E | |
| Gm7♭5 | G B♭ D♭ F | |
| G♯m7♭5 | G♯ B D F♯ | |
| Am7♭5 | A C E♭ G | |
| A♯m7♭5 | A♯ C♯ E G♯ | |
| Bm7♭5 | B D F A |
Frequently asked questions
What notes are in a half diminished chord?
1, flat 3, flat 5, flat 7. Bø7 is B D F A, Dø7 is D F A flat C, F sharp ø7 is F sharp A C E.
Why is it called half diminished?
Its triad is diminished but its seventh is a minor seventh, not a diminished seventh, so it is only "half" of a fully diminished seventh chord.
Is m7♭5 the same as half diminished?
Yes. Cm7♭5 and Cø7 are two names for the same chord: C E flat G flat B flat.
Where is the half diminished chord used?
As the ii chord in minor keys (Bø7 E7 Am in A minor) and as vii in major keys.