Learning diminished chords on guitar is a great way to expand your repertoire and can also be a great tool for song writing.
Not all styles of music make use of diminished (or augmented) chords but it’s still a good idea to have an understanding of what these are and how they can be used.
Chord Structure and Scale Structure
Before you can understand diminished chords you need to gain an understanding of chord structures and where they fit in a scale.
Every chord is made up of multiple notes – typically 3 or more. And the position of those notes within a scale will determine how that chord sounds.
So, let’s say for example we are in the key of C Major.
The notes in the key of C Major are C, D, E, F, G, A, B.
If we number each note, it makes it easier to see how chords are structured.
1st: C (aka root note)
In a major scale the sequence of intervals between notes is, from the root:
tone, tone, semi-tone, tone, tone, tone, semi-tone
There is only a semi-tone between the B and C and there is only a semi-tone between the E and the F as the E and B don’t have any sharps.
Now let’s look at a minor scale – let’s use A minor as an example:
1st: A (aka root note)
This follows the sequence:
tone, semi-tone, tone, tone tone, semi-tone, tone.
Minor and Major Thirds
Chords within a scale, at least those with 3 notes (aka Triads), are typically made up using:
the third and
The root could be any notes in the scale – so for an F Chord in a C major scale, the F becomes the root and then the A becomes the third and the C becomes the 5th – for that particular chord.
In the case of a major chord the 3rd is a “major third”. A 3rd is considered a major third when it’s 4 semi-tones above the root. So, if we take a C chord in the C major scale and go up four semi-tones from the root of that chord (in this case C) then we have:
C, C#, D, D#, E)
So we get to the major third, which in the case of a C major chord is E.
A minor third on the other hand is just 3 semi-tones above the root.
In the case of an A Minor chord in the A Minor scale, for example, the 3rd note from the root is a C. The A Minor chord is A C E, using the root, third and fifth notes.
So, in a minor chord, this is still the 3rd note from the root, but the way it’s positioned in the sequence means there are just three semitones above the root note – in the case of A Minor it’s (A, A#, B, C).
In a major scale the 3rd note is a major third, in a minor scale the third note is a minor third. And in a major scale the root of the scale will always be a major chord (e.g. C Major) and in a minor scale the root of the scale (e.g. A Minor) will always be a minor chord, because of the sequence of notes in the different scales. See below for what chords you get for each position of the scale (including where the diminished chord fits in).
Making up a Major Chord
We’ve discussed thirds, but to have a chord we also need the fifth. To make a major chord we need to have a root note, a major third and a fifth (the 5th is 7 semi-tones above the root).
So, for our C Major Chord in the C major scale, it would be the C, E and G. Playing C E and G together on the guitar will give you a C major chord. The E being the major third and the G being the fifth.
Making up a Minor Chord
To make a minor chord we need to have the root note, a minor third and a fifth. The only note that’s different between a major chord and a minor chord is the that the third is a minor third and not a major third.
So, in the case of the A Minor Chord in an A minor scale, the notes would be A, C & E. The C being the minor third and the E being the fifth.
There are minor chords in major scales too though and major chords in minor scales. And of course diminished chords! What type of chord each note in the scale will be depends on the position of that note in the scale.
Chord Progressions in a Scale
Major scales follow a natural chord progression. The root note is always a major chord. The progression for a Major scale is as follows – we will use roman numerals to represent the note numbers – as is common for chord progressions:
I: Major Chord
II: Minor Chord
III: Minor Chord
IV: Major Chord
V: Major Chord
VI: Minor Chord
VII: Diminished Chord
In the case of the C major scale this would be:
I: C Major
II: D Minor
III: E Minor
IV: F Major
V: G Major
VI: A Minor
VII: B Diminished
And this makes sense when you look at the notes.
C = C, E, G = C Major.
D = D, F & A (which is a minor chord since the F is a minor third (3 semi-tones)
E = E, G, B = E minor
F = F, A, C = F Major
G = G, B, D = G Major
A = A, C, E = A minor
B = B, D, F = B diminished
And for the minor scale:
I: Minor Chord
II: Diminished Chord
III: Major Chord
IV: Minor Chord
V: Minor Chord
VI: Major Chord
VII: Major Chord
For the A minor scale that would be:
I: A Minor
II: B Diminished
III: C Major
IV: D Minor
V: E Minor
VI: F Major
VII: G Major
But hang on, we haven’t discussed that diminished yet!
Making up a Diminished Chord
In the key of C major and A minor, we see that the B is a diminished chord – but what makes it a diminished chord.
Like major and minor chords the diminished chord uses the root, the 3rd and the 5th.
In the case of a major chord the 3rd is a major third and for the minor chord it’s a minor third. In the both the major and minor chords, the 5th is always 7 semitones above the root note – regardless of whether the third is a major or minor.
In the Diminished chord there is a minor third and a flattened fifth.
So, in the case of the diminished chord the third is 3 semi-tones form the root – and the fifth is 6 semitones from the root.
In the C major scale that we’ve been looking at the 7th chord is diminished. This is made up of B, D, F.
- The B is the root note
- The D is the third (in this case it’s a minor third – 3 semitones from the root)
- The F is the fifth (in this case a flattened 5th – 6 semitones from the root – B, C, C#, D, D#, E, F)
Put another way you could say that the third note in the diminished chord is a minor third up from the minor 3rd.
So, for Major chords it equals:
- Root note then the second note is 4 semi-tones up then the 3rd note is 3 semitones from the 2nd note in the chord.
For the Minor Chord:
- Root, then 3 semi-tones, then 4 semi-tones.
For the Diminished Chord:
- Root then 3 semi-tones, then 3 semi-tones.
Thanks for Reading
I hope this has helped you to understand what diminished chords are. If you have any questions regarding this or want to see more examples of this, feel free to leave a comment in the comments section below.