The Half-Diminished Chord

by Dennis Winge

 

The “half-diminished” and “diminished” chords are a common source of confusion for many music students.  Can we set the record straight?  I’m going to try to do this as quick and painless as possible.  Are you ready?

Triads

A triad is the 1st, 3rd and 5th note of any type of scale and typically come in 4 varieties:

A major triad is a root, major 3rd, and perfect 5th.

A minor triad is a root, minor (or flat) 3rd, and perfect 5th.

An augmented triad is a root, major 3rd, and raised (or sharp) 5th.

A diminished triad is a root, minor (of flat) 3rd, and lowered (or flat) 5th.

 

In order to hear these on guitar, play a real-life example in the key of A like this.  All examples are played on the 5th string:

A major = a, c#, e = frets 0, 4, and 7

A minor = a, c, e = frets 0, 3, and 7

A augmented = a, c#, f = frets 0, 4, and 8

A diminished = a, c, eb = frets 0, 3, and 6

 

7th chords

The difference between a half-diminished chord and a regular diminished chord only becomes apparent when we add the 7th to the triad.

A major 7 chord is a root, major 3rd, perfect 5th, and major 7th.

A dominant chord is a root, major 3rd, perfect 5th, and lowered (or flat) 7th.

A minor 7 chord is a root, minor (or flat) 3rd, perfect 5th, and lowered (or flat) 7th.

An augmented 7th chord is a root, major 3rd, raised (or sharp) 5th, and lowered (or flat) 7th.

A half-diminished chord is a root, minor (or flat) 3rd, lowered (or flat) 5th, and lowered (or flat) 7th.

A diminished 7th chord is a root, minor (or flat) 3rd, lowered (or flat) 5th, and twice-lowered (or double flat) 7th.

 

On guitar, again in the key of A on the 5th string, these look like the following.  Actually play these examples so you can hear them, not just read them on the page.

Amaj7 = a, c#, e, g# = frets 0, 4, 7 and 11

A7 = a, c#, e, g = = frets 0, 4, 7 and 10

Amin7 = a, c, e, g = frets 0, 3, 7, and 10

A+7 = a, c#, f, g = frets 0, 4, 8 and 10

Amin7b5 = A half-diminished = Aø = a, c, eb, g = frets 0, 3, 6 and 10

Adim7 = A diminished = a, c, eb, gb = Ao = frets 0, 3, 6 and 9

 

It’s important to notice that both the half-diminished chord and the diminished 7th chord share the same triad, i.e. root, flat 3rd and flat 5th.   This triad is called “diminished” which is potentially confusing for students because it has virtually the same name as the “diminished 7th chord.”  To add to the confusion, many musicians refer to a diminished 7th chord as simply a “diminished” chord.  

In order to keep it straight in your mind, simply use the terms “diminished triad” for the 3 note chord which is neither half-diminished or diminished 7th.  Use “half-diminished” to refer to a diminished triad with a flat 7th added, and use “diminished 7th” to describe a diminished triad to which a double-flat 7th has been added.  (The double-flat 7th is the same as the 6th scale degree by the way).  

 

Common Voicings

To play this chord on guitar, here are two common voicings that go with the same roots used for barre chords whose roots are on the 6th or 5th string.  


The most recognizable place that rock and blues players come across the first chord voicing above whose root in on the 6th string is in Led Zeppelin’s “Babe I’m Gonna Leave You” (which goes Am, Am/G, then Am/F# which is the same as F#m7b5).  And, the last diagram of the chord whose root is on the 5th string at the 2nd fret is commonly used in “Stormy Monday” (and in that case it functions as a G9 chord because it is being used in the context of a bass player playing G below it, but without the g note it is a Bmin7b5.)

 

Typical Uses

The half-diminished chord is found in the 7th position of any key’s harmonized major scale, as in the key of G:

I

II

III

IV

V

VI

VII

I

Gmaj7

Amin7

Bmin7

Cmaj7

D7

Em7

F#m7b5

Gmaj7

 
It is also the 2nd position in the pure minor harmonized scale as in Am:

I

II

III

IV

V

VI

VII

I

Am7

Bm7b5

Cmaj7

Dmin7

Emin7

Fmaj7

G7

Am7


Examples of their use in chord progressions are:

1.  |  G  |  C  |  F#m7b5  B7 |  Em  |

2.  | D7 | Em7b5  F#m7b5 | G |  G |

3.  | Am | Am/G | F#m7b5 | Fmaj7 |  (Am)


My suggestion is to memorize the 2 voicings above, so you’ll always have one handy off of either the 5th string or 6th string.  Knowing your half-diminished chords as well as regular barre chords, you can play your harmonized scales in all 12 keys.  They are very useful for understanding chord progressions, which applies to both songwriting and improvising.  Best of luck and have fun.


About the Author:  Dennis Winge is a pro guitarist and educator living in the Finger Lakes Region of New York State.  For guitar lessons in Ithaca, NY be sure to check out his school.