Gdim chord on guitar
Gdim (G diminished) is a diminished chord built on G. It has 3 notes, G, B♭ and D♭, and its formula is 1 ♭3 ♭5.
Notes and intervals of Gdim
From the root upwards, Gdim contains root (G), minor 3rd (B♭) and diminished 5th (D♭). Those intervals give the chord its colour: the formula 1 ♭3 ♭5 works the same way in every key, so once you know it for G you can build the chord on any note.
| Degree | Interval | Note |
|---|---|---|
| 1 | root | G |
| ♭3 | minor 3rd | B♭ |
| ♭5 | diminished 5th | D♭ |
How to play Gdim on guitar
The first shape above reads 3 1 x 3 2 x from the low E string to the high E string (x means you do not play that string, 0 is an open string). The lowest note you play is G. The other diagrams show the same chord higher up the neck: pick the one closest to the chords before and after it in your song.
This is a barre or movable shape: keep your index finger straight and close to the fret, and press with the side of the finger rather than the flat pad.
Which keys use Gdim?
You find Gdim as a diatonic chord in A flat major (vii°). The most common case is A flat major, where it plays the role of vii°.
Scales to play over Gdim
To improvise over Gdim, start with G blues scale. All of these scales contain every note of the chord: G blues scale and G Locrian mode. Aim for the chord notes on strong beats and use the other notes to move between them.
About diminished chords
Two stacked minor thirds: 1 ♭3 ♭5. The diminished fifth (a tritone) makes the diminished chord the most unstable triad: tense, dark and restless. It rarely stands alone and pulls towards the chord a semitone above its root. For example Bdim: B D F. Add a diminished seventh and you get the symmetrical diminished seventh chord.
In a major key it sits on vii° (for example Bdim in C major), acting as a lighter V7 that resolves to I. In a minor key it sits on ii°. Passing diminished chords connect neighbouring chords chromatically, for example I ♯i° ii (C C♯dim Dm). Classical music, jazz, ragtime and film scores use it to build suspense.
The triad is usually played as a small three or four-string shape on the middle or top strings, since full barres are awkward. Many guitarists play dim7 instead: a movable four-string shape that repeats every 3 frets, because the chord divides the octave into equal minor thirds. Slide it up three frets to hear a new inversion.
dim (three notes) and dim7 (four notes, with a diminished seventh) are not the same, though 'dim' on a jazz chart often means dim7. And dim is not m7♭5: the half-diminished chord adds a minor seventh (for example Bm7♭5: B D F A) and sounds much softer. Symbols: ° means diminished, ø means half-diminished.
Frequently asked questions
What notes are in the Gdim chord?
Gdim (G diminished) contains G, B♭ and D♭. In intervals: root (G), minor 3rd (B♭) and diminished 5th (D♭).
How do you play Gdim on guitar?
The easiest shape is 3 1 x 3 2 x, from the low E string to the high E string. This page shows 3 positions with finger numbers.
What scale goes with Gdim?
G blues scale fits Gdim best. Other scales that contain all its notes: G Locrian mode.
What key is Gdim in?
Gdim belongs to A flat major (vii°). In A flat major it is the vii° chord.
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