will explain the theory behind diminished guitar
chords and their function. There will be some overlap between this
lesson and the chord theory lessons, which show
you how to construct chords on guitar.
There's a lot of confusion around how diminished chords work in
music. I often get asked the question of "when to use them" in a chord
As with music in general, there's no hard and fast rules
(except "if it sounds good, play it!"),
but I'll take you through some of the tried and tested functions
diminished chords can
serve in your music.
Even if you were just looking for a chord
chart (which is further down the page), read through the whole lesson,
split over a few days,
as it will prove very rewarding as far
as developing your improvisation and songwriting skills.
Basic theory behind diminished chords
Diminished chords ("diminished" referring to the diminished
5th in the chord) have an
unstable sound. They create an air of tension and unresolve (hear the
examples below) which is what makes them wonderfully intriguing chords
to use in
are 3 main types of diminished chord, as shown in the table below.
Note that if you see
the ° symbol
after the chord letter (e.g. C°), it means "diminished". Some
people just use "o" as the proper symbol requires digging out the
As you can see, there's a common occurence of the root
(1), b3 (flat/minor 3rd)
(flat 5th) in the three types. These are the most important tones in
any diminished chord or scale. The flat 5th in relation to a minor 3rd
is what gives it that unstable quality.
So, a diminished triad
can simply be thought of as a minor
chord with a flat
A half diminished
chord is the above diminished
with an added flat 7th.
This chord is also sometimes written as m7b5 (minor 7 flat
5) e.g. Cm7b5.
A diminished seventh
chord is a diminished
triad with an added diminished
That's another way of saying "double flat 7th". So the only difference
between a dim7 and m7b5 chord is the 7th is flattened another semitone
in dim7 chords.
First, just make clear in your mind these
distinctions as each one has a different sound and function which we'll
look at shortly.
Diminished guitar chords chart
To help you play along throughout this lesson, here are the most common
diminished guitar chord forms used in chord progressions with their
Diminished triad chord chart
Half diminished chord chart
root note #2
Diminished seventh chord chart
root note #2
Diminished chords function
Firstly, occurences of the diminished triad
are often extended to half diminished or diminished 7th chords,
because they sound more... interesting. Essentially, you're playing the
diminished triad in both those variations anyway, so they're just a
meatier, more colourful version of the triad.
So, whenever there is an occurence of a diminished chord then you
should try both m7b5
(half diminished) or dim7
and go with the one that sounds best to you.
Let's look at some typical uses of the chord.
Leading tone diminished chord
a half diminished chord naturally occurs on the 7th degree
(called the leading tone). In plain English that means whatever the
major tonic chord is, the diminished chord naturally sits one
down from that.
It's called a "leading tone" or "leading chord"
because it naturally resolves or "leads" to the tonic. You can hear an
example here. See the table
below for a breakdown...
F / Bdim / C
Dm / Bdim / C
Am / Bdim / C
F# / Cdim / C#
Ebm / Cdim / C#
Bbm / Cdim / C#
C#dim / D
Em / C#dim / D
Bm / C#dim / D
just a few examples. You should be able to see this same leading tone
chord - tonic relationship no matter what key you're in.
In minor keys,
and especially minor keys based around harmonic minor, a
diminished 7th chord is the natural leading tone chord (click to hear
F / Bdim7 / Cm
F# / Cdim7 /
C#dim7 / Dm
Altered iii chord
In major key progressions, the iii
chord (naturally minor) is sometimes replaced with a half
You'll hear this most commonly used in jazz. For
What this does is destabilise the tonic for added interest.
Plugging whole step interval gaps
Essentially, you can fill any whole step interval between two chords in
a scale with a diminished 7th chord.
For example, the major diatonic scale is as follows...
can literally plug those whole step (W) gaps between the 1 and 2
chords, 2 and 3 chords, 4 and 5 chords, and 5 and 6 chords with a dim7.
Again, you'll hear this most commonly used in jazz, but there's no
reason why it can't be used in music in general.
If we were playing in the key of C, some examples of the above
technique would be as follows...