What Is a Diminished Chord?

Everything you need to know about diminished chords - from basic theory to advanced applications

Quick Reference: Diminished Chord Formula

Diminished Triad (dim)

1 - ♭3 - ♭5

Example: C dim = C - E♭ - G♭

Diminished 7th (dim7)

1 - ♭3 - ♭5 - ♭♭7

Example: C dim7 = C - E♭ - G♭ - B♭♭(A)

Diminished Chord Definition & Theory

What is a diminished chord? A diminished chord is a triad built from a root, minor third, and diminished fifth. The diminished chord creates tension and instability, making it perfect for transitions and resolutions in music.

The term "diminished" refers to the lowered (diminished) fifth interval. Unlike major and minor chords, diminished chords sound dissonant and unstable, which is why they're often used as passing chords or to create dramatic effect.

Key Characteristics:

  • Contains two minor thirds stacked together
  • Sounds tense and unstable
  • Often used as a passing chord or for modulation
  • Symmetrical structure (dim7 chords repeat every 3 frets/keys)
Types of Diminished Chords

1. Diminished Triad (dim or °)

The basic diminished chord with three notes.

C° = C - E♭ - G♭

2. Diminished 7th (dim7 or °7)

Adds a diminished seventh (double-flatted 7th) to the triad.

C°7 = C - E♭ - G♭ - B♭♭(A)

3. Half-Diminished (ø7 or m7♭5)

Uses a minor seventh instead of diminished seventh.

Cø7 = C - E♭ - G♭ - B♭
Diminished Chords on Piano

C diminished

Right hand fingering: 1-2-4

C - E♭ - G♭

C dim7

Right hand fingering: 1-2-3-5

C - E♭ - G♭ - A

Diminished Chords on Guitar

C diminished (open position)

Fret: X-3-4-5-4-X

Strings: X-C-G♭-C-E♭-X

Moveable dim7 shape

Root on 5th string

X-1-2-0-2-X

Common Uses of Diminished Chords

1. Passing Chords

Connect two chords chromatically:

C - C#dim - Dm - G7

2. Leading Tone Chords

Resolve up a half step to the target chord:

G#dim7 → Am

3. Substitution

Replace dominant 7th chords:

G7 → Bdim (shares 3 notes)

4. Modulation

The symmetrical nature allows easy key changes:

Cdim7 = Ebdim7 = Gbdim7 = Adim7
Practice Progressions
Try these progressions to hear diminished chords in context

Jazz ii-V-I with passing dim

Dm7 - D#dim7 - Em7 - A7 - Dmaj7

Classical resolution

C - G#dim/B - Am - F

Blues turnaround

C7 - A7 - Dm7 - G7 - C#dim7 - C7

Music Theory: Why Diminished Chords Work

The diminished chord's unique sound comes from the tritone interval between its root and fifth. This interval (6 semitones) is the most dissonant in Western music, creating the chord's characteristic tension.

The Symmetrical Secret

Diminished 7th chords are perfectly symmetrical - each note is exactly 3 semitones apart. This means any note in the chord can function as the root, making these chords incredibly versatile for modulation and voice leading.

Voice Leading Magic

Diminished chords excel at voice leading because they can resolve in multiple directions. Each note typically moves by just a half step to reach the target chord, creating smooth transitions that sound sophisticated and professional.