Adim7 Chord on Guitar
Adim7 = A – C – D# – F# (Root, Minor 3rd, Tritone, Major 6th)
A diminished 7th stacks four minor thirds in a row, making it the one chord in standard practice built from a completely symmetrical interval pattern. At the fifth-fret barre this symmetry has a direct physical consequence: the exact same fingering, moved up three frets at a time, produces the identical set of notes over and over.
The notes are A, C, D#, F# — root, minor third, diminished fifth, diminished seventh — and because each interval between them is an identical minor third, the chord can equally be called Cdim7, D#dim7 (Ebdim7), or F#dim7 (Gbdim7); all four names describe the same four pitches. Musically, Adim7 functions as a tense, highly mobile passing chord, most often heard leading chromatically into a chord a half step above one of its members, and it's a favorite tool for connecting distant keys precisely because relabeling its root gives a composer four different resolution options from the same fretted shape.
Fingerings
Barre (5th fret)
How to Practice It
Because the shape repeats identically every three frets, practice sliding this same barre fingering up the neck (fifth fret, then eighth, then eleventh, then back to the second) to internalize how one dim7 shape covers the whole fretboard's worth of diminished harmony. Try resolving Adim7 to four different major chords a half step above each of its four notes to hear how flexible its pull really is.
Common Progressions
- G – Adim7 – Am (a chromatic passing move raising G to A minor)
- A – Adim7 – Bm (a stepwise climb using the fully diminished passing chord)
- C – Adim7 – Dm (illustrating the shape's reuse a minor third away)
- E7 – Adim7 – Am (V7 – passing dim7 – i, delaying resolution)
FAQ
- What notes are in A diminished 7th?
- A, C, D#, and F# — four notes stacked in consecutive minor thirds, which is what makes the chord fully symmetrical rather than just tense like a plain diminished triad.
- Why can Adim7 also be called Cdim7 or F#dim7?
- Because every interval in the chord is an identical minor third, the four notes A, C, D#, and F# form a closed loop — starting the spelling from any one of them and calling it the root produces a chord with exactly the same pitches, just a different name.
- How many unique diminished 7th chords exist in total?
- Only three, since each one covers four roots a minor third apart; Adim7 (shared with C, Eb, and F#) is one of those three, alongside the two other symmetrical dim7 shapes built from the remaining pitches.
- What's the difference between Adim and Adim7?
- Adim is a three-note triad with no seventh, while Adim7 adds a diminished (double-flat) seventh on top, making it fully symmetrical in a way the plain triad isn't.
- Why is Adim7 useful for moving between distant keys?
- Since it can resolve convincingly to four different chords a half step above its four notes, a composer can use one Adim7 chord as a pivot to reach several different destinations depending on which resolution they choose, making it one of the most flexible passing chords in common use.
- Does the same barre shape work for all four of Adim7's names?
- Yes — because the fingering is identical no matter which note is treated as the root, sliding the same shape up or down by three frets simply relabels the chord without changing a single fretted note.
- Is Adim7 commonly used in guitar-based pop or rock?
- It's much rarer there than in jazz, classical, and musical-theater writing, where its tense, mobile quality and flexible resolution options are put to more deliberate use; in guitar-driven pop it mostly appears as a brief chromatic passing chord if at all.
Adim7 on other instruments: Adim7 on Piano. Related: how chords are built, chord finder.