m7b5 (m7-5) chords
The Minor 7th flat 5th
chord is an alternation of the minor seventh chord, and is also known as Half-diminished or Minor 7th minus 5th. This chord is identical to a minor seventh except that the fifth are lowered one step.
By comparing Cm7 with Cm7b5 we could see that the notes change from C, Eb, G, Bb to C, Eb, Gb, Bb.
The easiest way to play these chords are by the movable shape presented in the diagrams below (Am7b5 is partly an exception, with two open strings).
Minor 7th flat 5th
Am7b5 could of course also be played as x 12 13 12 13 x.
Alternative chord namesCm7b5 Cø
C#m7b5 C#ø / Dbø
D#m7b5 D#ø / Ebø
F#m7b5 F#ø / Gbø
G#m7b5 G#ø / Abø
A#m7b5 A#ø / Bbø
The minor seventh flat fifth is built with the formula 1-b3-b5-b7. This includes the root (1), the minor third (b3), a lowered fifth (b5) and the minor seventh.
Chord constructionCm7b5 x - x - C - Gb - Bb - Eb
C#m7b5 x - x - C# - G - B - E
Dm7b5 x - x - D - Ab - C - F
D#m7b5 x - x - D# - A - Db - Gb
Em7b5 x - x - E - Bb - D - G
Fm7b5 x - x - F - B - Eb - Ab
F#m7b5 x - x - F# - C - E - A
Gm7b5 x - x - G - Db - F - Bb
G#m7b5 x - x - G# - D - Gb - B
Am7b5 x - x - A - Eb - G - C
A#m7b5 x - x - A# - E - Ab - Db
Bm7b5 x - x - B - F - A - D
Guitar versions of the chord
Notes in chordCm7b5 C - Eb - Gb - Bb
C#m7b5 C# - E - G - B
Dm7b5 D - F - Ab - C
D#m7b5 D# - F# - A - C#
Em7b5 E - G - Bb - D
Fm7b5 F - Ab - B - Eb
F#m7b5 F# - A - C - E
Gm7b5 G - Bb - Db - F
G#m7b5 G# - B - D - F#
Am7b5 A - C - Eb - G
A#m7b5 A# - C# - E - G#
Bm7b5 B - D - F - A
The intervals are 1 – 3b – 5b – b7
Movable shape with root on sixth string
The half-diminished with the root note on the 6th string can be played as shown in the diagram below. Am7b5 is played 5X554X. To help you memorize, compare with the shapes Am7 (5X555X) and Am11 (5X553X).
Example of chord progression:
Bbmaj7 - Dm/F - F#m7b5 (2X221X) - C/G - D7 - G6
Movable shape with root on fifth string
This is the same shape as presented above and might be the most recognizable of the shapes for the half-diminished chord.
Movable shape with root on fourth string
And last, a movable alternative with the root on 4th string.
How and when to use half-diminished chords
These chords are, for example, used as an in-between chord. It can be used both in its own key or in other keys which its tones partly match.
In jazz, for example, m7b5 are often used in minor harmonies as the ii chord:
Am7b5 - Dm7 - Gm7
It can substitute 7th or 9th chords, for example, and especially the V chord. An example in which Em7b5 substitute the V chord:
Gmaj7 - Bm7 - Em7 - Em7b5 - Am7
Progressions including this chord type:
Am7 - Bm7b5 - E7
Am7 - Abm7b5 - G7
Dm7 - Dm7b5 - G7 - Cmaj7
C7 - Em7b5 - A7 - Dm7 - G7
Fmaj7 - Bm7b5 - Em7
Minor seventh flat fifth is often used as in between chord in blues and jazz progressions.
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