Half-Diminished Chords on Guitar: The m7b5 You're Missing

If you’ve studied jazz guitar or classical harmony, you’ve encountered a chord that sits between minor 7th and fully diminished - unresolved, tense, and uniquely expressive. That’s the half-diminished chord, also written as m7b5 (minor seven flat five).

It appears in virtually every jazz standard, shows up in classical cadences, and gives dark pop music much of its emotional weight. Once you can identify and play it, you’ll hear it constantly.

What Is a Half-Diminished Chord?

A half-diminished chord has four notes:

Root
Minor 3rd (b3)
Diminished 5th (b5)
Minor 7th (b7)

The formula: 1 - b3 - b5 - b7

Compare this to:

Minor 7th: 1 - b3 - 5 - b7 (the 5th is perfect, not diminished)
Diminished 7th: 1 - b3 - b5 - bb7 (the 7th is doubly flattened)

The half-diminished sits between these two. It has the diminished 5th of the fully diminished chord but the milder minor 7th instead of the diminished 7th. “Half” diminished - one element is diminished, one is not.

B half-diminished (Bm7b5): Notes: B - D - F - A

You’ll recognize these notes as the ii chord in the key of C major (built on the 7th scale degree). In jazz, it almost always appears as the ii chord in a minor key ii-V-i.

Half-Diminished Guitar Shapes

Bm7b5 (Common Shape, Root on 5th String)

e|---0---|
B|---3---|
G|---2---|
D|---1---|
A|---2---|
E|---x---|

This is one of the most practical half-diminished shapes. Root on the 5th string at fret 2.

Am7b5 (Root on 5th String, Open Position)

e|---0---|
B|---1---|
G|---1---|
D|---2---|
A|---0---|
E|---x---|

Am7b5: A - C - Eb - G. The b5 is Eb, giving it that distinctive unsettled quality.

Em7b5 (Root on 6th String)

e|---0---|
B|---3---|
G|---0---|
D|---2---|
A|---2---|
E|---0---|

Em7b5: E - G - Bb - D. You’ll see this in the key of F major (built on the 7th degree).

Moveable Shape (Root on 6th String)

e|---x---|
B|---4---|
G|---3---|
D|---4---|
A|---5---|
E|---3---|  (root: G, giving Gm7b5)

Move this shape and you get any half-diminished chord with the root on the 6th string.

Where Half-Diminished Appears

The Minor ii-V-i

This is the primary home of the half-diminished chord in jazz. In the key of A minor:

Am7b5 - D7 - Gm (or Gmaj7, depending on context)

Compare this to the major key ii-V-I you may know:

Major: Dm7 - G7 - Cmaj7
Minor: Em7b5 - A7 - Dm (in D minor)

The half-diminished ii chord plus the dominant 7 creates a dark, brooding sound that resolves to the minor tonic. This progression is the backbone of countless jazz ballads and dark standards.

In Classical Music

Beethoven and Chopin use half-diminished chords extensively as “leading tone chords” that pull strongly toward resolution. The tense, unresolved quality makes them perfect for dramatic moments before a cadence.

In Pop and Film Music

Dark pop progressions often include the half-diminished. Radiohead, Nick Cave, and many film composers use it for ominous or emotionally complex moments.

The Difference: Half-Diminished vs Fully Diminished

Play these back to back:

Bdim7 (fully diminished):

e|---x---|
B|---3---|
G|---4---|
D|---3---|
A|---2---|
E|---x---|

Bm7b5 (half-diminished):

e|---0---|
B|---3---|
G|---2---|
D|---1---|
A|---2---|
E|---x---|

The fully diminished sounds more symmetrical, almost sci-fi tense. The half-diminished sounds more human - melancholic and unresolved rather than jarring.

Soloing Over Half-Diminished Chords

For improvisers: the Locrian mode (the 7th mode of the major scale) fits over half-diminished chords. But many jazz players prefer the Locrian #2 mode (the 6th mode of the melodic minor scale), which raises the 2nd scale degree for a slightly smoother sound.

For chord players, simply knowing where the chord sits in a progression (almost always as the ii in a minor key ii-V-i) gives you context for how to voice it and lead into the V chord that follows.

Try This in Guitar Wiz

Half-diminished (m7b5) chords are available in Guitar Wiz’s Chord Library. Search for any root note followed by “m7b5” to see the voicings. Look at how the b5 creates that distinctive interval gap in the middle of the chord shape.

To practice the minor ii-V-i, use Song Maker to build a progression: try Em7b5 - A7 - Dm. That’s a minor ii-V-i in D minor - one of the most common jazz cadences. Play through it slowly with deliberate voicings and notice how the half-diminished creates tension that the A7 amplifies, before the Dm resolves it.

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FAQ

Is m7b5 the same as half-diminished?

Yes. “Half-diminished” and “m7b5” (minor seven flat five) refer to the same chord type. “Half-diminished” is the classical/jazz name; “m7b5” is the more descriptive chord formula name.

How is half-diminished different from diminished?

A diminished triad has a minor 3rd and a diminished 5th. A half-diminished chord adds a minor 7th on top. A fully diminished 7th chord has a diminished 7th (double flat) instead.

Where do I most commonly encounter half-diminished chords?

In jazz, as the ii chord in minor key ii-V-i progressions. Also in classical music as a leading tone chord, and in dark pop and film music.