G#dim piano chord, G# diminished notes and fingering.

The G#dim piano chord is G# diminished: the notes G#, B and D. It is two minor thirds stacked on top of each other. G# up to B is three semitones, and B up to D is three more, so the fifth (D) is lowered to six semitones above the root. Chord charts write it as G#dim or G#°.

How to play G#dim on piano

1. Find G# on the keyboard. G# is the middle black key of the group of three, between G and A. It is the same key as Ab.
2. With your right hand, put finger 1 on G#, finger 3 on B and finger 5 on D. Finger 1 is the thumb.
3. Press all three keys together. In root position they run from G#3 to D4, a reach of 6 semitones. Play chord sounds them together and Arpeggio sounds them one by one, from the bottom up.
4. Click Left hand to see the left hand. It plays G#2 to D3, one octave lower: G# with finger 5, B with finger 3, D with finger 1.
5. The cards under the keyboard hold the three positions, with G#, B and D at the bottom in turn. Play and Arpeggio on a card play that position.
6. Open Note names. As written the keys read G#, B and D. Sharps shows G#, B and D, and Flats shows Ab, B and D. This chord is written with sharps, so As written and Sharps match.

How G#dim is built

Counted from the root, the formula is 0, 3, 6. Stacked on each other the gaps are 3 + 3: two minor thirds. Compare it with G# minor (G#, B and D#): the first two notes are the same, and the fifth is lowered one semitone from D# to D. A perfect fifth is seven semitones; this one is six, and six semitones is a tritone.

Worked example: the pitch of G#3. On a piano tuned to A4 = 440 Hz, a note 13 semitones below A4 has the frequency 440 × 2^(-13/12), which is about 207.65 Hz. B3 is 10 semitones below A4, so 440 × 2^(-10/12) gives about 246.94 Hz.

G#dim and Abdim are the same chord on the keyboard: the same three keys sound for both. Written as Abdim it would need a double accidental (Ab, Cb and Ebb), so G# is the name that sheet music uses.

What the keys look like under your hand

The white keys beside G# are G on the left and A on the right, a semitone each way. One of the three notes is a black key (G#) and two are white keys (B and D). Your thumb lands on G#, a black key with G and A beside it. Keep the thumb relaxed and slightly curved, and let the wrist stay level instead of twisting to reach.

G#dim inversions and fingering

G#dim has three positions. In root position G# is at the bottom. In the first inversion, B is at the bottom and the chord is written G#dim/B. In the second inversion, D is at the bottom and the chord is written G#dim/D. The tightest reach, 6 semitones from the lowest key to the highest, is the root position. The widest, at 9, is the first inversion and second inversion.

The keys that hold G#dim

G#dim fits two of the major and natural minor keys that have a standard key signature, which means every note of it comes from that key's scale. The simplest is A major, with 3 sharps, where it is chord vii°.

Progressions that use G#dim, with the chord numbers and the chords in that key:

• A major: IV-vii°-iii-vi, which is D, G#dim, C#m, F#m, a run of falling fifths.
• F# minor: ii°-v-i, which is G#dim, C#m, F#m, the minor ii-V-i, with the natural minor v.
• A major: vii°-I, which is G#dim, A, the diminished chord leading up to the tonic.

Here is a worked example in A major. The chord before G#dim in the first progression above is D (D, F# and A). From D in root position, the closest way to reach G#dim is its second inversion (D, G# and B, lowest note first): one note stays where it is, and the others move 4 semitones in total, counting each note against the note in the same place from the bottom.

G#dim also sits inside E7 (E, G#, B and D): take the root off that dominant 7th and the notes left over are G#, B and D.

What G#dim sounds like

A diminished triad sounds tense and unresolved. It rarely sits still: the usual move is up a semitone to the chord built on A. It is used as a passing chord between two others and as a spice inside a progression.

G#dim is the vii° chord in A major and the ii° chord in F# minor. It is also chord vii° of A minor, using the raised seventh of the harmonic minor scale.

A common mistake with G#dim

A common mistake is pressing D# instead of D, one semitone higher than the fifth of G#dim. That gives G#m (G#, B and D#), a plain minor chord. The top key of G#dim is a semitone lower than you might expect, so check it against the chord of the same root.

Chords to learn next

Chords close to G#dim: G# minor (raises the fifth; shares G# and B); E7 (the dominant 7th it sits inside; contains all its notes); A major (the chord it leads to; shares no note); G#m7 (adds a minor seventh to the minor chord; shares G# and B).

Once G#dim feels easy, play it and then A major to hear it resolve upward. For chords beyond these six types, and for guitar and ukulele shapes, use the chord finder. To play along with your computer keys, open the virtual piano. The piano chords page lists all 72 chords.