Scales and modes
Diminished scale
The diminished scale is a symmetrical eight-note scale that alternates half steps and whole steps, used over 7♭9 dominant chords and diminished seventh chords.
What is the diminished scale?
The diminished (or octatonic) scale has eight notes and alternates half and whole steps evenly. It comes in two forms, depending on which step comes first:
- half-whole: 1 ♭2 ♭3 3 #4 5 6 ♭7. In G: G A♭ B♭ B C# D E F.
- whole-half: 1 2 ♭3 4 ♭5 ♭6 6 7. In C: C D E♭ F G♭ A♭ A B.
Half-whole is the one guitarists use most: heard from G, it contains the ♭9 (A♭), #9 (B♭), third (B), #11 (C#), 13 (E) and ♭7 (F).
How do you play the diminished scale on guitar?
G half-whole diminished around the 2nd and 3rd frets, three notes per string:
| String | Frets | Notes |
|---|---|---|
| 6 | 3, 4, 6 | G A♭ B♭ |
| 5 | 2, 4, 5 | B C# D |
| 4 | 2, 3, 5 | E F G |
| 3 | 1, 3, 4 | A♭ B♭ B |
| 2 | 2, 3, 5 | C# D E |
| 1 | 1, 3, 4 | F G A♭ |
The scale repeats every minor third: move the shape three frets and you are still in the same scale. G, B♭, C# and E half-whole share the same notes, so there are only three different diminished scales. Like the whole-tone scale, it is one of the symmetric scales in the Pro library of the guitar scales tool.
Which chords does the diminished scale fit?
- Half-whole over a dominant seventh chord with a ♭9: G7♭9, G13♭9, G7(♭9,#9). Thanks to the symmetry, the same scale also covers B♭7, C#7 and E7.
- Whole-half over a diminished seventh chord: Cdim7 (C E♭ G♭ A), for example as a passing chord between C and Dm.
Shortcut: G7♭9 (G B D F A♭) contains Bdim7 (B D F A♭). Over a ♭9 dominant, playing a diminished arpeggio from the third already gives you the sound of the scale.
Exercise: G7♭9 to C
- Play G7♭9: 3 x 3 4 3 4 (G, F, B, D, A♭).
- Play the B D F A♭ arpeggio: G string 4th fret, B string 3rd and 6th frets, high E string 4th fret.
- Move the same arpeggio up three frets (G string 7th, B string 6th and 9th, high E 7th): D F A♭ B, same notes, new inversion.
- Resolve to C, aiming for E on the B string, 5th fret.
Shifting by minor thirds like this is a signature move of gypsy jazz and bebop.
Key takeaways
- Eight notes, alternating half-whole or whole-half.
- Half-whole over 7♭9 dominants, whole-half over dim7 chords.
- Minor-third symmetry: every lick moves by three frets.
- Only three distinct diminished scales exist.
Frequently asked questions
What is the difference between half-whole and whole-half diminished?
They are the same note cycles started from different places. G half-whole has the same notes as A♭ whole-half. Pick by chord: 7♭9 dominants for the first, dim7 chords for the second.
Why are there only three diminished scales?
Because the scale repeats every minor third (three half steps). The twelve possible roots fall into groups of four, which leaves only three different sets of notes.
Does the diminished scale work over a plain dominant chord?
It adds the ♭9, #9 and #11, so it creates strong tension. Over an unaltered G7 it sounds deliberately outside; save it for moments when the dominant really needs to pull toward its resolution.
Related terms
Practise in the workshop
Take it from theory to the fretboard
Open the workshop tools and see this idea across the whole neck. Free account, no card needed.