How a Diminished Chord Is Created

Learn about diminished intervals in music, and why they sound so strange

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Diminished chords, like major and minor chords, occur naturally in every key, and each key has only one diminished chord.

Intervals in a Diminished Chord

A diminished chord is built similarly to a minor chord, except for its fifth. It consists of the following intervals:

  • Root: The note upon which a chord is based, no matter its inversion. F# is the root of F#dim; B is the root of Bdim, and so on.
  • Minor 3rd: An interval of three half steps above the root note (compared to four half steps with a major third).
  • Diminished Fifth: Six half steps above the root (compared to seven half steps with a perfect 5th).

Compare the following B chords (click for sound):

  • B Major: B-D#-F# (major 3rd, perfect 5th)
  • B Minor: B-D-F# (perfect 5th)
  • B Diminished: B-D-F (dim 5th)

Character and Mood of Diminished Chords

A diminished chord’s character is best described as ambiguous. When heard alone, diminished chords can be perceived as eerie, goofy, or even annoying. When heard within music, diminished chords often create the desire for tonal resolution; they tend to “leave the listener hanging.” Observe this concept for yourself:

  1. Listen to the B diminished chord alone
  2. Hear a B diminished chord resolved by a B major chord

Diminished Chords and “Dissonance”

The reason for a diminished chord’s bizarre sound is its tonal instability (or “dissonance”). The intervals in a diminished triad, for example, are equally spaced – there are three intervals between B-D, and also between D-F – and this lack of harmony within the chord is what causes the ear to seek tonal resolution.

In a minor chord, the perfect fifth is what provides resolution; but in a dim chord, the fifth has been flattened. This leaves the chord with two intervals of 1.5 steps (minor thirds ), stripping it of a focal point. Because diminished chords leave so much to be desired, they are often transitional or used to enhance musical climaxes.

Abbreviating Diminished Chords

In piano music, diminished chords can be abbreviated as follows:

  • Bdim/Bdim7
  • B°/B°7 (sometimes seen as Bo in type)
  • Bmb5 - meaning Bm (B minor), b5 (flattened fifth)
  • vii° – where “vii” signifies the seventh chord in a major scale.*
  • ii° - signifying the second chord in a minor scale.*
    *The seventh chord in a major scale is identical to the second chord in its relative minor scale. is chord vii° in C major, but chord ii° in A minor.

Learn More About Scales and Key Signatures

What Are the Forgotten Key Signatures? The circle of fifths shows only the working scales. But, if we expand on its pattern, we can see that it’s actually more of an infinite spiral, so there’s no end to the possibilities of musical scales. One could write a song in the key of B quadruple-flat; learn more.

Easy-to-Read Breakdown of the 15 Key Signatures. Most notes of the staff name both major and minor key signatures, but some are only seen as one or the other. A few keynotes don't name any working key signature, and their scales are considered rare or theoretical. Consult this table to learn more, and to strengthen your understanding of the diatonic scale.

The Diatonic Scale: Comparing Major & Minor. Major and minor are often described in terms of feelings or mood. The ear tends to perceive major and minor as having contrasting personalities; a contrast that is most obvious when the two are played back to back. Learn more about major and minor scales and keys.

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