G Diminished Chord (Gdim)

1Composition: what it contains

G – B♭ – D♭

Symbol

Gdim

Also written

Gdim, G°, Gm♭5, Gmi(♭5)

Formula

1 ♭3 ♭5

2Appearance: diagrams and sound

On the guitar

On the ukulele

On the piano

On the staff

On bass and as an arpeggio

3Indications: what it is used for

The vii° chord of a major key and the ii° chord of a minor key are diminished triads. It works as a leading-tone chord resolving to the tonic (vii°–I), as a passing chord between two diatonic chords (for example between I and ii, or IV and V), and as an incomplete dominant seventh: the vii° triad contains the 3, 5 and 7 of V7. Classical, jazz, gospel and film music use it for tension and chromatic movement in the bass.

4Dosage: how to practise it

On piano, play the triad in all inversions at 60 BPM, then practise vii°6–I resolutions with smooth voice leading (the diminished fifth contracting to a third). On guitar, learn the compact three-string shapes on the top strings and the shape rooted on the fifth string. Practise the passing progression I–♯I°–ii–V slowly, then at 80–100 BPM. Arpeggiate 1-♭3-♭5 on bass. Five minutes a day is enough once the shapes are known.

5Warnings and common mistakes

Do not confuse the triad (dim) with the diminished seventh chord (dim7 or °7) or the half-diminished seventh (m7♭5 or ø7): many charts write 'dim' when they mean the four-note dim7, so check the style. The diminished fifth is not a perfect fifth; on guitar, power-chord habits make players play the wrong fifth. In root position the triad can sound harsh; first inversion is the most common classical voicing.

6Interactions with chords, scales and keys

Inversions

• Inversion 1 · Gdim/B♭ · B♭ – D♭ – G Play
• Inversion 2 · Gdim/D♭ · D♭ – G – B♭ Play

Scales to play over Gdim

• G Locrian Mode
• G Blues Scale
• G Half-Whole Diminished Scale
• G Whole-Half Diminished Scale
• G Hungarian Minor Scale
• G Altered Scale

Where it appears (keys and Roman numerals)

• vii° – Key of A flat Major
• ii° – Key of F Minor

7Other presentations available

The same chord from every note

Cdim C♯dim Ddim E♭dim Edim Fdim F♯dim A♭dim Adim B♭dim Bdim

Other chords on G

G Gm Gaug Gsus2 Gsus4 G5 G6 Gm6 G7 Gmaj7 Gm7 Gm7♭5 Gdim7 Gm(maj7) G7sus4 Gadd9 Gm(add9) G6/9 G9 Gmaj9 Gm9 G11 Gm11 G13 G7♭9 G7♯9 G7♯5 G7♭5