Diminished Scales: Everything You Need to Know

James Melton
July 22, 2024

GOOD FOR

Diminished scales are incredibly useful tools for improvisers and are necessary for jazz musicians to understand! The unique nature of the diminished scale makes it a strong choice when trying to hit certain sounds in your improvisation.

However, many musicians don’t take full advantage of everything the diminished scale offers!

That’s why I will break down everything you need to know about diminished scales and show you all the cool ways you can use the diminished sound to your advantage when soloing.

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Diminished Scales Overview

We must learn what it is before taking full advantage of the diminished scale. Here’s the best way to understand diminished scale theory.

The diminished scale is an octatonic scale (meaning eight notes) comprised of a series of alternating half-steps and whole steps (or whole steps and help steps, depending on where you start).

[H-W]-[H-W]-[H-W]-[H-W]
[W-H]-[W-H]-[W-H]-[W-H]

When you start with the half step, you are playing the half-whole diminished scale. When you start with the whole step, you are playing the whole-half diminished scale.

Therefore, there are two types of diminished scales:

Half Whole Diminished scale (also known as the Dominant Diminished scale)
Whole-half diminished scale

Think of these two scales as the “modes” of the diminished scale. Diminished scales and the chords you can build from them appear way back in ancient music history. They most likely entered Western music through the cultural exchanges with the Middle East during the late Middle Ages and Renaissance.

Let’s learn more about each mode of the diminished scale.

1. Half-Whole Diminished Scale

Here is a half-whole diminished scale (which means we start with the half-step). Another name for this eight note scale is the dominant diminished scale.

C diminished scale (half-whole):

Diminished scales: Eight tones of the dominant diminished scale on staff with steps visualized

[H-W]-[H-W]-[H-W]-[H-W]

2. Whole-Half Diminished Scale

Bb diminished scale (half-whole):

Diminished scales: Whole-half diminished scale on staff with steps visualized

[W-H]-[W-H]-[W-H]-[W-H]

These two scales are the same! One starts with the half step, and the other starts with the whole step.

Symmetrical Scales

Another important aspect of diminished scales is that they are symmetrical scales!

Symmetrical scales divide an octave into equal parts or have a repeating interval pattern that gives them symmetry.

What are examples of a symmetrical scale?

To better understand symmetrical scales, let’s explore a few types.

Whole Tone Scale

The whole tone scale consists of six notes, each a whole step (tone) apart.

W-W-W-W-W-W
C-D-E-F#-G#-A#-C
The whole tone scale divides an octave into six even parts vial whole steps.

Chromatic Scale

The chromatic scale consists of twelve notes, each a half step (semitone) apart.

H-H-H-H-H-H-H-H-H-H-H-H
C-C#-D-D#-E-F-F#-G-G#-A-A#-B-C
The chromatic scale divides an octave into twelve equal parts via half steps.

Diminished Scale (Octatonic Scale):

The diminished scale consists of eight notes alternating whole and half steps.

W-H-W-H-W-H-W-H
C-D-Eb-F-F#-G#-A-B-C (whole-half diminished scale)
The diminished scale divides an octave into four even parts via couplets of whole steps and half steps—either [W-H] or [H-W].

Interestingly, when you combine symmetrical scales, you lose that symmetry. The altered scale, also known as the super-Locrian scale, is the seventh mode of the melodic minor scale. It combines the diminished scale with the whole tone scale but loses its translational symmetry.

The first half of the altered scale looks diminished, but the second half looks like a whole tone scale:

Diminished scales are symmetrical scales that have translational symmetry. This means you can translate your starting note up to the next [H-W] or [W-H] pair, and you’d still have the couplet of scale steps. The only difference is that you start from a different point in the sequence.

Another way to think of these scales is to see them as made up of four [W-H] or [H-W] pairs. When you add a whole step to a half step, you get a minor third. Four minor thirds give you an octave!

C diminished scale:

Symmetrical scale; breaking a diminished scale into four even couplets of half and whole steps

Comparing Symmetrical Scales to Asymmetrical Scales

All diatonic scales, like the major scale, natural minor scale, or their modes, are asymmetrical, which means they don’t break up an octave evenly. This means each note in the major scale formula has a unique series of steps, leading to seven unique modes that only repeat after an octave.

The major scale sequence, or any other asymmetrical scale, only repeats after one octave. There are no smaller, even groupings of steps. This is why diatonic scale and diatonic modes are asymmetrical.

On the other hand, the four pairs of half and whole steps that make up diminished scales evenly divide an octave into four pieces and have translational symmetry.

There Are Twelve Major Scales, But Only Three Are Diminished Scales!

Because diminished scales have translational symmetry based on units of half steps and whole steps (equivalent to minor thirds), there are only three unique diminished scales.

Compare this to major scales, which only repeat the major scale sequence after one octave. Because of this, there are twelve major scales.

Let’s find out why there are only three diminished scales. We will use the guitar fretboard to visualize the reason. The guitar fretboard’s linear, half-step structure makes the nature of diminished scales easy to see.

You can clearly see the repeating series of half steps and whole steps on the guitar!

Let’s use the half-whole diminished scale and overlay the scale pattern on the guitar. Here is an E diminished scale:

E dominant diminished scale on the guitar fretboard

E-F-G-Ab-Bb-B-Db-D-E
[H-W]-[H-W]-[H-W]-[H-W]

Let’s overlay the same type of scale starting a half step up from before:

F dominant diminished scale on the guitar fretboard; half whole scale

This gives us a new sequence of notes and, therefore, a unique diminished scale:

F-Gb-Ab-A-B-C-D-Eb-F
[H-W]-[H-W]-[H-W]-[H-W]

Let’s try the process a third time! Here is the same diminished scale sequence starting on Gb

Gb dominant diminished scale on the guitar fretboard

Again, we have a unique sequence of notes and another diminished scale.

Gb-G-A-Ab-C-Db-Eb-E-Gb
[H-W]-[H-W]-[H-W]-[H-W]

However, when we try to do this again and start the same sequence on G, we end up with the first sequence of notes. The blue color also helps to illustrate this.

After translating the scale up three half steps, we return to the same notes as our first sequence. The only difference is that we are starting on G instead of E.

G-Ab-Bb-B-Db-D-E-F-G
[H-W]-[H-W]-[H-W]-[H-W]

This is a visual example of the diminished scale’s translational symmetry. It also explains why there are only three diminished scales! Using the half-whole diminished scale as our reference (it is one of the two modes, after all), we can identify all three diminished scales:

E Diminished scale
- It is the same as the G diminished scale, Bb diminished scale, and Db diminished scale.
F Diminished Scale
- It is the same as the Ab diminished scale, B diminished scale, and D diminished scale.
Gb Diminished Scale
- It is the same as the A diminished scale, C diminished scale, and Eb diminished scale.

That’s it! There are only three!

BEFORE YOU CONTINUE...

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Harmonizing the Diminished Scale

We need to understand what chords you can build from these scales to use them in our improv. When we harmonize the diminished scale sequence in thirds, we end up with two diminished seventh chords separated by a half step.

Finding two diminished chords in the diminished scale

Here, it is seen a different way, where each root note is its own diminished chord:

C diminished scale harmonized in diminished seventh chords

Improvisational Uses For The Two Diminished Scales

Now that we know all about the diminished scale and how it works, let’s learn how to use it when improvising! As we established, there are two “modes” or flavors of diminished scale:

Half whole diminished scale (dominant diminished scale)
Whole half diminished scale

Diminished Scales and Dominant Chords: How To Use Diminished Scales

The diminished scale’s unique qualities make it especially useful for playing over b7 dominant seventh chords. Let’s take a C7b9 dominant chord and look at each chord tone. When we isolate the 3rd, 5th, 7th, and b9th, we end up with a fully diminished seventh chord.

In this case, an E°7chord:

Therefore, when we put an E diminished seventh chord over a C root note, we get all the same notes as a C7b9 chord. In fact, we can build a diminished chord off of the b9, 3rd, 5th, or 7th and get all the same notes as a rootless C7b9 dominant chord:

Building diminished chords off of specific chord tones in a dominant chord to get inversion of a C7b9 chord

However, we don’t have to stop there! Any of the notes in our diminished chord can be the b9 of a different dominant chord. That means we can imply four different dominant chords with one diminished chord.

Here is that same process if we count E as the b9 in a 7b9 chord, giving us an Eb7b9 chord:

building an Eb7b9 chord from a diminished chord

Here it is if we count the G as the b9 in a 7b9 chord, giving us a F#7b9 chord:

building an F#7b9 chord from a diminished chord

And finally, here it is when we count the Bb as the b9 in a 7b9 chord, giving us an A7b9 chord:

building an A7b9 chord from a diminished chord

That’s one diminished chord and four dominant chords!

C7b9
Eb7b9
F#7b9
A7b9

Using Dominant Diminished Scales Over a ii-V-I

To use dominant diminished scales over a ii-V-I, you want to start the diminished line on the root, the #9, the #11, or the 6th. If you use a dominant diminished scale, you start on a half step, so you want to place your line on these chord tones.

Rt
#9
#11/b5
6th

Here is an example of a ii-V line starting on the tonic note of the G7b9 chord.

Using the half-whole diminished scale over a ii-V-I chord progression

Using Whole-Half Diminished Scales Over a ii-V-I

You want to start your scale on the b9, the 3rd, the 5th, or the 7th to use the whole half diminished scale over a ii-V-I.

Here is an example of a ii-V line starting on the b9 of a G7b9 chord:

Using the whole-half diminished scale over a ii-V-I chord progression

Diminished Scales and Diminished Seventh Chords

The whole half diminished scale is best for playing over diminished chords, both diminished triads and fully diminished seventh chords. As mentioned above, you can also play the whole-half diminished from certain chord tones in a dominant chord.

Fully-diminished chords only appear naturally in harmonic minor scales. Below is an A harmonic minor scale harmonized in seventh chords. The chord built off the leading tone, or seventh scale degree, is a fully diminished seventh chord.

However, jazz musicians use diminished chords when comping over changes. You’ll often find diminished chords written into the changes of many jazz standards, so knowing how to play over them is essential.

Let’s look at the B section of the tune “Softly, As In A Morning Sunrise.” The chord progression often uses diminished chord substitutions in place of dominant chords, just like we discussed above!

The B section of "Softly, As In A Morning Sunrise"

You can play an E whole-half diminished scale over the Edim7 chord. Likewise, you can play a G, Bb, or Db whole half-diminished scale because they are the same scale.

And, because of the scale symmetry, it’s the same as playing a C, Eb, Gb, or A half-whole diminished over this diminished chord. These eight options are all the same notes!

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Diminished Scales: Everything You Need to Know

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