Diminished 7th Chords

Chord Theory
A Diminished 7th chord is a dissonant or unstable chord and generally needs resolution. Guitarists often play the diminished 7 or dim7 (4-note chord) instead of the diminished triad (dim) or 3 note chord.
  • dim7 chords are 4 note chords consisting of 3 minor 3rds above the root or tonic, therefore having a root, a minor 3rd, a diminished 5th and a diminished 7th.
  • The chord formula for a dim7 is 1 - ♭3 - ♭5 - ♭♭7(6)
  • The symbols for a diminished 7th chord are, dim7 or º7
  • The featured song for this session using dim7 chords is 'Love is a Losing Game' written and performed by Amy Winehouse... some excellent backing by the guitarist and bass player.
  • For Country Music Fans we have another featured song by Patsy Cline called Crazy. It has a great melody with some very nice diminished 7 chords and a vast array of barre chords. Every learning guitarist will enjoy playing this one.

Example: Calculating C diminished 7th... Cdim7 or Cº7 

  • Diminished 7th chords consist of the 1st, ♭ 3rd, ♭5th and ♭♭7th notes of a Major Scale
  • Remember that a minor third is equal to 3 half steps or 3 semitones. If we move a minor third upwards from C, we get E♭...(C - C# - D - E♭). If we move another minor 3rd upwards from E♭, we get G♭... (E♭- E - F - G♭). If we move another minor 3rd upwards from G♭, we get B♭♭... (G♭ - G - A♭ - B♭♭)... B♭♭ is actually an A. We call it a B♭♭ because it is the 7th note of the C diatonic scale which is B.
  • Remember that all chords are based around the major scale of that chord, therefore C chords are built from the C major scale which consists of no sharps or flats. The scale reads as follows: C - D - E - F - G - A - B - C
  • Formula for a dim7 chord = 1 - ♭3 - ♭5 - ♭♭7
  • Substitute the notes into the formula: 1=C, ♭3=E♭, ♭5=G♭, ♭♭7=♭♭B(A)
  • Cdim7 reads as follows: C - ♭ E - ♭G - B♭♭(A)
Diminished 7th Chord Table
dim 7 A A# B♭ B C C# D♭ D  
Root A A# B♭ B C C# D♭ D  
♭3rd C C# D♭ D E♭ E F♭ (E) F  
♭5th E♭ E F♭ (E) F G♭ G A♭♭ (G) A♭  
♭♭7th G♭ G A♭♭ (G) A♭ B♭♭ (A) B♭ C♭♭ (B♭) C♭ (B)  
dim 7 D# E♭ E F F# G♭ G G# A♭
Root D# E♭ E F F# G♭ G G# A♭
♭3rd F# G♭ G A♭ A B♭♭ (A) B♭ B C♭ (B)
♭5th A B♭♭ (A) B♭ C♭ (B) C D♭♭ (C) D♭ D E♭♭ (D)
♭♭7th C D♭♭ (C) D♭ E♭♭ (D♭) E♭ F♭♭ (E♭) F♭ (E) F G♭♭ (F)


Diminished 7th Chord Charts

Adim7 - Cdim


Diminished 7th Chords




C#dim7 / Dbdim7 - Edim7


Diminished 7th Chords

Please note that all chord charts indicate different shapes in different fret positions rather than set fret positions. Generally, there are 3 different dim7 shapes and each one can be played in 4 different positions. Let's say that you like playing the third shape, and you are looking for a Ddim7 chord... as long as the shape stays intact and any one of your 4 fingers lands on a D note, you are playing a Ddim7 chord. The same applies to the other shapes.




Fdim7 - G#dim7/ Abdim7


Diminished 7th Chords




Hope you enjoyed this session. As you learn more and more chords, you will start to see patterns taking shape. Take note of these and whenever you can, try to remember your chord formulas. The more you play, the easier they are to remember.