In music, harmony is one of the most important aspects of creating a song, alongside melody and rhythm. And the most fundamental building blocks of harmony are chords. There are many different types of chords, with Major and Minor being the most famous.
This post will cover one specific type of chord, looking at what exactly is a Half Diminished Chord. First, however, we need to understand better what a chord is.
What is a Chord?
A chord is when two or more notes are played at the same time.
The number of notes is usually between 2 and 4 – a chord with two notes is called an interval or a dyad, a chord with three notes is called a triad, and the most popular type of chord with four notes is a seventh chord.
With triads and Seventh chords, you create the chord by stacking intervals of a 3rd on top of each other.
For example, a major triad is made with two intervals of a 3rd.
A major 3rd and a minor third which in C would be C, E and G.
To make a minor triad you stack a minor 3rd followed by a major 3rd which in C would be C, Eb and G.
On top of these triads you can add a 7th, which is just either a Maj 3rd (for a Maj7 chord) or a min 3rd (for a 7 chord or min7 chord) above the top note.
So, in a Seventh chord, you have these notes:
|Maj7 Chord||7 Chord (dominant 7)||Min7 chord|
|Root (the note of the chord)||Root||Root|
|3rd (Maj 3rd above root)||3rd (Maj 3rd above root)||3rd (min 3rd above root)|
|5th (min 3rd above 3rd)||5th (min 3rd above 3rd)||5th (Maj 3rd above 3rd)|
|7th (Maj 3rd above 5th)||7th (min 3rd above 5th)||7th (min 3rd above 5th)|
For more information on chord qualities and the different types of triad check out our guide to chords here.
What is a Half Diminished Chord?
A Half Diminished chord is a particular type of Seventh chord.
It is a chord with a min7th above a diminished triad.
A diminished triad is a chord with two minor 3rds stacked on top of each other.
Check out our post on diminished chords here for further reading.
Instead of a Maj-min 3rd stack, like a Major chord, or a min-Maj 3rd stack, like a minor chord, a diminished chord is min-min 3rds.
From this diminished triad, we can add a 7th to get a Seventh chord.
If we add a min7th, which is a Maj 3rd above the diminished 5th interval produced by the triad, then that is considered a half diminished chord.
This is an C half diminished chord – it has a Cdim triad on the bottom (C – Eb – Gb) and then a min7th (Bb) on top.
This is slightly different from a fully diminished 7th chord which would have a B double flat instead of a B flat.
In a major scale, a half diminished chord is found naturally starting on the VII scale degree.
So, in C, that means if you take a seventh chord starting on B and only using the notes found in the C Maj scale (no accidentals), then you get the half diminished B – D – F – A.
This is also known as the locrian mode.
In a minor scale, the half diminished chord is found naturally starting on the II scale degree.
In C minor, this would be D – F – Ab – C.
Half Diminished Chord Symbol
Because the half diminished chord is a Seventh chord, it usually has a “7” written in the chord notation.
The half diminished part is notated by a circle with a line through it – “ø”.
Another way you can see a half diminished chord written is as a minor 7th chord with a flattened 5th – Cmin7b5 or G#m7(b5) for example.
Sometimes there are parentheses around the b5, but not always.
So, a half diminished chord is written as Cø7, Fø7, Dø7, Gø7, or you could use m
Sometimes you see the chord written without the 7 – such as Cø or Ebø.
Even though there’s no 7 in the chord, it’s still a seventh chord because the “ø” symbol means “half diminished” and that has to be a seventh chord.
Function of Half Diminished Chords
A ø7 chord has two primary harmonic functions.
First, it can act as a predominant chord in minor, one that leads to the dominant.
This is because in the minor scale the chord built on scale degree II – which is always a predominant chord – is a half diminished chord.
Here is an example in A min:
In Major, the ø7 chord usually provides a dominant function, leading back to the tonic (main chord of a song).
This is because a viiø7 chord shares almost all of the same notes as a V7 chord in a Major key.
For example, in C Maj, the G7 (G – B – D – F) and Bø7 (B – D – F – A) share the B, D, and F in common, meaning the Bø7 chord can act as a stand in for the G7 chord.
Examples in Music
In the famous “Wedding March” by Mendelssohn, the big chord at the beginning of the main melody is an F#ø7.
Listen for it at 0:16.
Chopin’s “Scherzo No. 1 in B Minor” starts with a long-held C#ø7 chord.
In the song “We are the Champions” by Queen, there is a Bbø7 in the line “And I mean to go on, and on, and on, and on…” listen at 0:36 for the second “on”.
We hope that this post really helped you learn all about Half Diminished Chords.
They are really interesting to play and to use in compositions because they have multiple functions, and can sound really different depending on the context they’re played in.
They sometimes sound and feel super dark and minor, and other times can be energetic and Major.