A♭dim7: G♯/A♭ Diminished 7th Piano Chord

Root position: either hand, fingers low note to high
Hand	Notes	Fingers
Right	A♭, C♭, E♭♭, G♭♭	2-3-4-5
Left	A♭, C♭, E♭♭, G♭♭	5-4-3-2

Scale degree, note, and interval measured from the root.
Degree	Note	Interval from root	Semitones
1	A♭	Perfect unison	0
♭3	C♭	Minor third	3
♭5	E♭♭	Tritone	6
♭♭7	G♭♭	Major sixth	9

Construction

A♭ Diminished 7th = Root + Minor 3rd + Diminished 5th + Major 6th = A♭, C♭, E♭♭, G♭♭

Note	Interval	Degree
A♭	Root	1
C♭	Minor 3rd	♭3
E♭♭	Diminished 5th	♭5
G♭♭	Major 6th	6

Fingering

Note	Key color	Right hand	Left hand
A♭	black	index finger (2)	little finger (5)
C♭	white	middle finger (3)	ring finger (4)
E♭♭	white	ring finger (4)	middle finger (3)
G♭♭	white	little finger (5)	index finger (2)

Right hand: index finger (2) on A♭, middle finger (3) on C♭, ring finger (4) on E♭♭, little finger (5) on G♭♭.

Left hand: little finger (5) on A♭, ring finger (4) on C♭, middle finger (3) on E♭♭, index finger (2) on G♭♭.

A♭ Diminished 7th Inversions

Root position
A♭ – C♭ – E♭♭ – G♭♭
1st inversion (A♭dim7/C♭)
C♭ – E♭♭ – G♭♭ – A♭
2nd inversion (A♭dim7/E♭♭)
E♭♭ – G♭♭ – A♭ – C♭
3rd inversion (A♭dim7/G♭♭)
G♭♭ – A♭ – C♭ – E♭♭

Key Signature

A Diminished 7th chord is built from symmetrical or ambiguous intervals, so it doesn't belong to a single key and has no key signature of its own.

Chords in the Key of A♭ Major

These are the triads built on each degree of A♭ Major:

I — A♭ Major (major)

Degree	Numeral	Chord	Quality
1	I	A♭ Major	Major
2	ii	B♭ Minor	Minor
3	iii	C Minor	Minor
4	IV	D♭ Major	Major
5	V	E♭ Major	Major
6	vi	F Minor	Minor
7	vii°	G Diminished	Diminished

Same Notes, Other Names

The notes A♭ – C♭ – E♭♭ – G♭♭ aren’t exclusive to this chord. Depending on which note is the bass and how the chord functions, the same pitches also spell the following:

B Diminished 7th→D Diminished 7th→F Diminished 7th→

A♭ Diminished 7th : Frequently Asked Questions

What notes are in A♭dim7?

A♭dim7 contains A♭, C♭, E♭♭ and G♭♭. The formula is 1, ♭3, ♭5, ♭♭7.

How do you play A♭dim7 on piano?

Play A♭, C♭, E♭♭ and G♭♭ together. Right hand fingers 2, 3, 4, 5; left hand 5, 4, 3, 2. A♭ is a black key; C♭, E♭♭ and G♭♭ are white.

What are the inversions of A♭dim7?

4 positions: root position A♭ C♭ E♭♭ G♭♭, A♭dim7/C♭, A♭dim7/E♭♭, A♭dim7/G♭♭.

What is the difference between A♭dim7 and A♭dim?

Drops G♭♭. 3 of the notes are shared.

What is an easy A♭dim7 for small hands?

The guide tones, ♭3 and ♭♭7 voicing, C♭3 G♭♭4, spans 6 semitones or about 83 mm.

What are the frequencies of A♭dim7?

From A♭3 at A440 in 12-TET: 207.65, 246.94, 293.66, 349.23 Hz.

What is the set class of A♭dim7?

Prime form (0369), Forte 4-28, interval vector <004002>.

How do I transpose A♭dim7 to another key?

Keep the 1, ♭3, ♭5, ♭♭7 formula on the new root. C♯dim7 is C♯, E, G, B♭; Ddim7 is D, F, A♭, C♭.

Is G♯dim7 the same as A♭dim7?

Enharmonically yes: the same piano keys and the same sound, spelled differently.

A♭ Diminished 7th in detail

Exact

Every pitch class is present and nothing outside the chord is added.

Type	Notes	Semitones	Span	Omissions and additions	Set relation
Close, root position	A♭3 C♭3 E♭♭4 G♭♭4	9	124 mm	none	identical
Close, first inversion	C♭3 E♭♭4 G♭♭4 A♭4	9	124 mm	none	identical
Close, second inversion	E♭♭4 G♭♭4 A♭4 C♭4	9	124 mm	none	identical
Close, third inversion	G♭♭4 A♭4 C♭4 E♭♭5	9	124 mm	none	identical
Drop 2	E♭♭3 A♭3 C♭3 G♭♭4	15	206 mm	none	identical
Drop 3	C♭2 A♭3 E♭♭4 G♭♭4	18	248 mm	none	identical
Drop 2 and 4	A♭2 E♭♭3 C♭3 G♭♭4	21	289 mm	none	identical

Reduced

A subset of the pitch classes: the identity is incomplete rather than altered.

Type	Notes	Semitones	Span	Omissions and additions	Set relation
Shell, root ♭♭7 ♭3	A♭2 G♭♭3 C♭3	15	206 mm	omits E♭♭	subset
Guide tones, ♭3 and ♭♭7	C♭3 G♭♭4	6	83 mm	omits A♭ and E♭♭	subset
Rootless close	C♭3 E♭♭4 G♭♭4	6	83 mm	omits A♭	subset

Spans are measured centre to centre at a 165 mm octave (standard keyboard geometry).

Position	Bass note	Notes in order	Figured bass	Semitones	Span
Root position	A♭	A♭3, C♭3, E♭♭4, G♭♭4	7	9	124 mm
First inversion: A♭dim7/C♭	C♭	C♭3, E♭♭4, G♭♭4, A♭4	6/5	9	124 mm
Second inversion: A♭dim7/E♭♭	E♭♭	E♭♭4, G♭♭4, A♭4, C♭4	4/3	9	124 mm
Third inversion: A♭dim7/G♭♭	G♭♭	G♭♭4, A♭4, C♭4, E♭♭5	4/2	9	124 mm

One position per chord tone in the bass. Spans are for close position: voiced inversions appear under Voicings.

Change one note

Chords a single note away, and what moving that note does.

Chord	Change	Formula	Common tones
A♭dim	drops G♭♭	1 ♭3 ♭5	3
A♭m7♭5	G♭♭ becomes G♭	1 ♭3 ♭5 ♭7	3
A♭m6	E♭♭ becomes E♭	1 ♭3 5 6	3
A♭m	E♭♭, G♭♭ becomes E♭	1 ♭3 5	2
A♭m7	E♭♭, G♭♭ becomes E♭, G♭	1 ♭3 5 ♭7	2
A♭mMaj7	E♭♭, G♭♭ becomes E♭, G	1 ♭3 5 7	2
A♭6	C♭, E♭♭ becomes C, E♭	1 3 5 6	2

Frequencies

Note	MIDI	Frequency
A♭3	56	207.65 Hz
C♭3	59	246.94 Hz
E♭♭4	62	293.66 Hz
G♭♭4	65	349.23 Hz

Reference pitch A440, 12-TET, close root position.

Set theory: prime form, Forte number, interval vector

Absolute pitch class set: {8, 11, 2, 5}
Normal order: [2, 5, 8, 11]
Prime form: (0369)
Forte number: 4-28
Interval vector: <004002>

Pair	Interval	Semitones	Interval class
A♭ to C♭	Minor third	3	3
A♭ to E♭♭	Tritone	6	6
A♭ to G♭♭	Major sixth	9	3
C♭ to E♭♭	Minor third	3	3
C♭ to G♭♭	Tritone	6	6
E♭♭ to G♭♭	Minor third	3	3

Where these facts come from

Every value on this page is derived from the note formula for a diminished 7th applied to the root A♭, using standard music theory. Nothing here is hand-entered per chord, so the notes, intervals, inversions and frequencies cannot drift out of agreement with each other. Pitches assume 12-TET at A440.

A♭ Diminished 7th

Fingerings

A♭ Diminished 7th: notes and degrees