Music TheoryChordsHarmony

What Is A Diminished Chord In Music?

Written by Samuel Chase

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Most music that you hear on the radio or play in a band is made up of chords. There are many different types of chords, but the four most common types are major chords, minor chords, augmented chords, and diminished chords.

In this post, we’ll take a look at diminished chords – what are they, how do you make one, and what is their purpose in music? But first, let’s go back and recap just exactly what a chord is.

What is a Chord? 

Music is made up of pitches or notes. A chord is any time you hear two or more notes played at the same time.

When just two notes are played, this is called a dyad, or an interval.

While these technically are considered chords, when you hear the term chord it almost always means three or more notes. 

A chord with three notes is called a triad, and chords that have more than three notes are often referred to as extended chords which could include seventh chords, ninth, eleventh, or even thirteenth chords.

Here are a few examples of chords: 

Chord examples

A typical triad starts with a tonic note, which is the bottom note.

It then adds a note that is a 3rd above it, and a third note that is a 3rd above that note.

The difference between major, minor, augmented, and diminished chords are if the 3rd intervals between the notes are major 3rds or minor 3rds.

Diminished Chords Explained

Diminished chords are a type of chord that are either played with three notes – a diminished triad – or four notes – a diminished seventh chord.

There are few different types of each one, but let’s start by looking at diminished triads.

Diminished Triads

A diminished triad is built from two minor 3rds stacked on top of each other.

A minor 3rd is an interval with the size of 3 semitones (or half steps).

For example, here is a C diminished triad (also written as Cdim).

C Diminished Triad

Starting on C (the root note) – a minor 3rd above that is the note Eb, so C⇨Eb is a minor 3rd.

From Eb⇨Gb is another minor 3rd, so the triad of C, Eb, Gb is a diminished triad. 

Other diminished triads are:

  • Ddim = D, F, Ab
  • Edim = E, G, Bb
  • G#dim = G#, B, D
  • Adim = A, C, Eb
  • Bdim = B, D, F

Diminished chords are noted for their sound, which is very dark and a bit scary.

Just like a minor chord sounds sadder and darker than a major chord, a diminished chord is even more dark and sad.

It has within it an interval called a tritone, which is the single most unstable interval in all of music.

It is an interval of 6 semitones, and looks like this:

C⇨Gb a diminished 5th or the enharmonic equivalent, C⇨F# an augmented 4th.


Diminished Sevenths

There are two types of four-note chords that are diminished, and they’re called diminished sevenths.

There is the half-diminished 7th chord, and the fully-diminished 7th chord.

Both of these chords start with a diminished triad as the first three notes, but have a different top note.

Half diminished chords

The half-diminished 7th chord takes a diminished triad and adds an interval of minor 7th on top.

This note is a Major 3rd above the top note of the underlying triad.

For example, with the Cdim triad (C, Eb, Gb), if we added a note that is a Major 3rd above the Gb (4 semitones higher), then we get a Bb.

So a chord with C, Eb, Gb, Bb is a C half-dim 7th chord.

C Half diminished 7th chord

Fully Diminished Chords

The second type of diminished 7th chord is a fully diminished 7th.

This is where instead of a major 3rd interval on top of the diminished triad, we add a minor 3rd instead.

In the key of C this means we add a B double flat us Gb⇨Bbb is a minor 3rd) then you get a fully diminished 7th chord.

So, the Cdim triad becomes C, Eb, Gb, Bbb as a fully-diminished 7th chord.

Diminished 7th chord

Notating Diminished Chords

When writing out the chords, using the full word “diminished” is a lot and leaves you very little space to write anything else, so you need a symbol to mean diminished instead.

When we write a diminished triad (three notes) we use what looks like a degree symbol, ° or as dim.

So we could write a diminished triad with a ° or dim after it.

Notating diminished triads

For a half-diminished 7th chord, we take the ° symbol and put a line through it, so it looks like this: ø7.

We can also write it as m7 b5 which means the same thing.

Half diminished 7th chords

For a fully-diminished 7th chord, we use the same ° symbol, but add a 7 after it, like this: C°7 or by writing dim7.

Diminished 7th chords

Examples of Diminished Chords in Music

There are many examples of diminished chords being used in popular music.

“We are the Champions” by Queen has one after the line “We’ll keep on fighting ‘til the end”: 

“We are the Champions” by Queen

The chorus of the song “All Star” by Smash Mouth goes G – C – C#° – C, listen to it here:
“All Star” by Smash Mouth

Lastly, the classic by The Beach Boys, “God Only Knows”, has two different diminished chords in its verse.

Here’s it being sung by the Pentatonix, because it’s easier to hear.

Listen around the lyrics “You’ll never need to doubt it, I’ll make you so sure about it.”

“God Only Knows” – Pentatonix

And in Classical music, here is an excerpt from the First movement of Mozart’s “Piano Sonata No. 11 in A Major”, K. 331.

In bar 12, there is a short D#° triad that leads from the main key of A Major to a modulation to E Major.
First movement of Mozart’s “Piano Sonata No. 11 in A Major”, K. 331

That’s It For Diminished Chords

We hope this article was able to help you figure out exactly what diminished chords are and how they work.

They’re very dark sounding and can be used in scary music sometimes as well, and because they’re unstable, they are often short, passing chords.

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Samuel Chase has been playing music since he was 5 years old, and teaching music since he was 13. He has a PhD in Music from the University of Surrey, and he has composed music that has been played in three different countries. He is currently working as a film composer and writing a book on film music.