Half-Diminished Chords Explained for Guitar: m7♭5 Theory & Voicings

What is a Half-diminished Chord?

Minor 7 flat 5 chord is close to a diminished 7th chord, the first 3 notes are identical, but the 4th is different.

This chord can be written in two ways: m7b5 or Ø. If you do not know how to play and what is a diminished 7th chord, you can read this page about diminished chord voicings. 

As is it shown in the chart below, the half-diminished chord is built with a root (1), a minor third (b3), a flat fifth (b5) and a minor 7th (b7). The diminished 7th chord has a diminished 7th instead of the minor seventh.

This is the only difference between these two chords.

You can find the half-diminished chord in a number of harmonized scales.

For example the 7th degree of the major scale, the 2nd degree of the harmonic minor scale and the 6th and 7th degree of the melodic minor scale.

Harmonized Major Scale

When you harmonize in thirds the degree VII of the major scale you obtain a m7b5 chord.

Harmonized Harmonic Minor Scale

When you harmonize in thirds the degree II of the harmonic minor scale you get a m7b5 chord.

Harmonized Melodic Minor Scale

When you harmonize in thirds the degrees VI and VII of the major scale you obtain two m7b5 chords.

This lesson lists the main tools to improvise over half-diminished chords. 

Half-Diminished Guitar Chord Diagrams 

Here are the three main m7b5 guitar chord shapes.

The first one is drop 3 voiced whereas the two other voicings are drop 2.

How To Use Half-Diminished Chords?

Half-diminished chords are mostly present in minor II V I progressions, example with Dm7b5.

The half-diminished chord is specially a leading chord, the sound strongly pulls towards resolution.

It is possible to use it as a diatonic substitution for a dominant 7th chord.

Try to play the m7b5 a major 3rd higher than the dominant 7 chord to replace it. For example, use Bm7b5 for G7. 

• This II-V-I : Dm7 | G7 | Cmaj7 becomes Dm7 | B-7b5 | Cmaj7

You can use the m7b5 as a substitution for a minor 7th chord, built from a minor third below. It means that you can replace Dm7 chord with Bm7b5.

• This II-V-I : Dm7 | G7 | Cmaj7 becomes Bm7b5 | G7 | Cmaj7

Comparison With Minor 6

The minor seventh flat five chord is also an inversion of the minor 6 chord.

This is a minor 6 chord with the sixth in the bass.

Here is a comparison between them.

As you see in the guitar neck diagrams below, the minor 6 and m7b5 chord shapes are exactly the same. 

Notice that half-diminished chords can also be considered as rootless 9th chords as explained in this lesson.